Finally put up a system... mostly so that people can see what my recommendations/opinions are based upon. Feel like I'm getting closer all the time, but it's very much still a work in progress. Fairly happy with the current sound, but am very interested in trying out different (digital) sources and working with the gear to make the sound as warm and inviting as possible.
A LITTLE HISTORY: I bought my first stereo equipment from Wal-Mart when I was 13 and have been into music and music reproduction ever since. Got some big MTX speakers for my 16th birthday, and got into hi-fi when I was in graduate school at Ohio State University. Lived in shared houses for many years and have been a bad neighbor on many weekend nights... I'm sorry folks, thanks for your tolerance.
PAST SYSTEMS: Built around 2005 when I first joined the site, my first real system was a pair of Thiel 1.6s driven by a Classe CAP-151 and an Exemplar modified Denon 2910. The Classe won out over a Bel Canto eVo2i I also auditioned. Five years later I upgraded to Thiel 2.4s, driven by a Pass Labs INT-30A and PS Audio Perfectwave DAC. The INT-30A won out over a Pass Labs X250.5 and a McIntosh MC402.
After blowing yet another set of Thiel drivers and seeing the company be on the ropes after Jim's death, I did a lot of reading to figure out what to do next. Based on the recommendations of member Charles1dad, I ended up moving to the high efficiency Coincident Super Eclipse IIIs (92db sensitivity, 14ohm impedance). One draw of these speakers was that they would allow me to try different amplifier topologies. After purchase, I put my Pass Labs INT-30A up against a First Watt SIT-2 and a pair of 8W Coincident Frankenstein 300b monoblocks. Loved, loved, the all Coincident combination and the experience piqued my interest in trying the company's top of the line speakers, the Pure Reference Extremes. Although challenging, they are the cornerstone of my current system.
SPEAKERS: The 94db, 8 ohm Coincident PREs have only a single capacitor and single inductor in their crossover. The mid-range driver goes straight to the amplifier. The capacitor provides high pass filtering for the accuton ceramic tweeter. It responds very strongly to capacitor changes and (as promised by others) I've found the Duelund tinned copper CAST to be the best. Despite being advertised as having Mundorfs, my PREs came with the run of the mill Solens pictured above. I replaced those with ClarityCaps bypassed by Duelund .01uF sliver foils, replaced those with Jupiter Copper Foils, and then replaced those with the Duelunds. The ClarityCaps were "ruler flat", the stock Solens were a bit noisy, but with some nice color/richness, and the Jupiters combined the best attributes of the two. The Duelunds are better in every way. Natural, rich in color, and somehow also the most accurate/detailed of the bunch. Highly recommended. I found I didn't like the sound of adding bypass capacitors to the speaker crossover, as it seemed to produce some smearing or phasiness that made me uncomfortable.
As recommended by member Grannyring, I run the speakers with unterminated Duelund tinned copper in oiled cotton cables -- 16ga on the top and 12ga on the bass. These are way better than the anti-cables I had from the previous system. Curious to try more cables, but also hesitant to go down the rabbit hole. I also saw that Jim Smith uses these cables on his current (2019) system... seems like another solid recommendation.
AMPLIFICATION: Despite the advertised specs, the Coincident PREs are less efficient than the Super Eclipses IIIs and I was forced to search out new amplifiers to replace my beloved Coincident Frankenstein 300bs (run with Mullard CV378 rectifiers and EML XLS 300bs). The Franks simply couldn't drive the PREs in the low frequencies and would start to distort on loud music.
I tried a Lyngdorf 3400, Atma-Sphere M60s, and a Pass Labs XA25, but in each case settled on the Franks despite their poor bass performance. Eventually I decided to built a DIY First Watt F4. It only provides current gain and my plan was to use it as a booster amp to power the PREs' bass units while being driven directly by the speaker outputs of the Franks. Unfortunately, bi-amping killed the speakers' coherency. That was also true when I tried pairing the Franks & Lyngdorf using the latter's active crossover.
To my surprise, when I tried the F4 as the sole amplifier of the PREs it beat out the Franks. It retained a great deal of the sweetness of the Franks, improved the bass, improved clarity, and reduced distortion. Soundstaging is also amazing. Perhaps there's been a small reduction in tonal color. After having it in the system for a month, I put the Franks back in and it was clear that there was no going back. The F4 is based on a simple, no feedback Class A circuit and the PREs really sing with them. These speakers really do seem to prefer simplicity.
Although a single F4 is plenty of power for the speakers, I built a pair of monoblocks to keep speaker wire runs short. This also allows me to do a vertical biamp solution, with each of the PRE's four cabinet boxes getting its own 25w amplification channel. Plus no R/L channel crosstalk. Thank you to Nelson Pass and the diyaudio.com/passlabs community for providing the resources and technical support that allowed me to build such wonderful amplifiers.
The F4s use custom 12ga Furutech FP-S032N based power cords from member Grannyring's Acoustic BBQ line.
PREAMPLIFIER: Adding the Don Sachs 6SN7-based preamp has greatly improved the sound of my system and I simply can not go back to using my DAC direct. This was true both with my PS Audio Perfectwave DAC that has a less than ideal volume control (i.e., it throws away bits below a certain level) and with the PS Audio Directstream DAC's improved volume control (full resolution at all levels). This pre seems to just make the music better in every way. It is not at all syrupy or tubey, just passes on the sound of the source and makes it better.
Having gotten into modding my gear, I also like that the preamplifier is based on a kit (the VTA SP-14) that I can read about so I can learn the circuit. That fact and the unit's two separate outputs lines encouraged me to try different capacitors. Don recommends Miflex copper foils, but I found them a bit two-dimensional and veiled in my system. I installed Mundorf Supremes and found that the system was capable of a lot more front to back layering than revealed by the Miflexs. I then put in Mundorf Supreme Silver/Gold/Oils. They added in a nice touch of richness over the plain Supremes while retaining all the wonderful soundstage depth. Very happy with the current sound, but will continue to try out various competitors. TFTF V-Caps just got installed.
As recommended by Don, I run the preamp with a pair of Shuguang Black Treasure CV181zs as the main tubes. They're complimented with a wonderful pair of RCA grey glass VT231s as the buffer tubes. Compared to CV181zs in all positions, adding in the RCAs reduces the pre's punch/impact a bit, but adds in some smoothness and layering. I use the standard 6X5GT rectifier Don provides.
The preamplifier connects to my F4s via Ocellia Silver Reference RCA interconnects and is powered by a DIY DH Labs Red Wave AC cord with Furutech copper screw on connectors. I tried building my own DIY interconnects using the Duelund 16ga wires and KLEI absolute harmony plugs, but the Ocellia cables were significantly better.
SOURCE: Despite its age, the PS Audio Perfectwave DAC MKII is really a great sounding piece of equipment. I'm sure there are better units out there, but it is a very functional piece that allows me to switch between my three digital sources (network audio, TV for Ohio State football & video streaming, and a PS4). Critically, it's also a highly musical, natural sounding piece. I've tried to move on twice (2015 & 2019) and have gone back both times. Adding in the Bridge II network card made the DAC much, much, better and allows me to stream CD-quality music directly from Tidal (served by BubbleUPNP running on an Android tablet) without having a computer in the rig. Again, highly recommended. I miss buying music, but am never going back to spinning disks. Tidal often sounds better than my ripped music collection as well.
I run the PWD with a SR Blue fuse in the digital slot and a Furutech fuse in the analog slot. It's connected to my router with a Supra ethernet cable, and is powered by a DIY DH Labs Power Plus AC cord with Chinese copy Furutech Rhodium screw on connectors. It connects to my preamplifier using balanced MIT cables (a lost model number from many years ago).
ROOM: Some compromises have been made in order to blend the stereo with a video system and drop it into the primary living space. I'd love a dedicated room, but would also suffer greatly removing the system from living room where it is the daily driver for music, a show or two, and some PS4 play. The room is 19' across, 16' deep, with 23' peaked ceilings. It opens up to the rest of the house in two places. Half of the "back wall" is open to the dining room, which drops back another 9'. The 23' vaulted ceiling also opens up to a second story master bedroom/loft space. This all makes it so that the stereo is basically in charge of pressurizing the entire house except for a spare bedroom and small basement. Fortunately I am able to set it up in such a way that the speakers are not parallel or perpendicular to any walls. It's on the room diagonal, a placement forced by the location of the front door and attached dining room.
This has a couple benefits, one being that the equipment cabinet and TV can be pushed further back away from the speakers. The second is that the traditional side wall first reflection points aren't a problem. Aside from a rug over the hardwood floor, there are no room treatments... don't really know where to put them.
POWER, CABLES, ETC: As much as I'm loath to admit it, I have found that all of these tiny variables matter. This wasn't really true (or the impact was too small to care) with my other systems, but the Coincident PREs reveal the impact of every small change. This has made it clear that cables, power cords, and fuses can have a very substantial impact. I find it incredibly frustrating that I don't understand how or why the fuses or power cords could possibly matter, but in this system they do. Again, curious to try more than my current DIY solutions, but also scared to go down the path...
Based on recommendations from Ralph Karsten @ Atma-Sphere, I purchased an Elgar 6006B to condition the power to my system. I run everything except my amplifiers off of its perfect sine wave. Given its age, it is recommended to replace all capacitors in the unit, which is on my to do list. Unfortunately I can't get myself to listen to the stereo without it in the chain, so I haven't gotten around to "fixing" my unit yet. The PREs' accuton tweeters can get aggressive and removing distortion from the incoming power is essential to keeping them warm and inviting. Note that this unit must be installed in a separate room, as its (industrial) fan and transformer are both too loud for a listening room. Also, it's heavy AF. I purchased the Elgar because despite the dedicated lines, I still got some electrical feedback from various objects at the stereo (e.g., a slight pop noise when an LED bulb was turned on). The Elgar has completely eliminated that issue.
The stereo is on its own dedicated circuit with two 10ga romex lines both run off the same leg of the incoming power. The Elgar runs one line, and my amps reside on the other.
Happy to field comments. Hopefully some folks find the information useful. Thanks to all the people who have written about their experiences and thereby helped me build the system... almost all of it was purchased blind without prior exposure, so finding some trustworthy voices out there in the digital forest has been incredibly useful. Thanks folks.