My GF owned the Butler home and the tube driver 5150, it's nice but it's really a hybrid design and it's just using the tube as a buffer stage. I would probably like the Milbert amplifiers more, they were designed by David Berning and are ZOTL designs quite likely similar to the one that John Atkinson used to use as his reference amplifier which was once a Berning.
I've considered using those for mid range and for the high-end, and just using the McIntosh for midbass and bass. I also have a TTVJ portable tube amp...which I could toss in as a buffer...but the Nakamichi REMOTE Tuner preamp the TD 1200 special shop edition does a fine job as a preamp.
I am just trying to integrate a fine sounding DAC into the system. I used the Hegel HD 25 at RMAF 2014 in a room I tuned for Chapman audio it did excellent and was reviewed with much more costly systems. I think it would be near perfect in a car because to change inputs you just tap the faceplate. The sound has great depth and air, as well as a sense of Hall and recording space at is for the most part completely absent in other DACs at this price range. Furthermore, the components within it are not the end of the line audiophile grade...but the circuit design gives it much of its good sound... So it could be easily modded to make it even more true to life sounding.
I have an apogee mini DAC, it is amazingly good in a car, needs no warm up, and runs off of any voltage from 6-14 volts.
I heard the Hugo (not as smooth has some odd audio issue in bass- to be fair it got a quick listen, but I also tried the chordate Qute and that was not as good either and is very power supply dependent) and definitely prefer the HEGEL HD 25 , I also heard the HEGEL SUPER which was not nearly in the same class as the HD 25. I have also considered the Lynx Studio Hilo which can run from 12 volts but runs hot, and has a confusing interface..though it also is a nice AD converter. I had the WADIA smaller pieces, and they are nothing like the WADIA 860x GNSC. Which I use in one of my systems at home. I also considered the MSB analog DAC but it has 4 power supplies 12 volts, -12 volts, 24 volts ,-24 volts and I have used it with and wit hour the additional external pover supplies and I found that the power supply quality makes in Normas difference with this unit so to put it in a car or the power is not exactly stable probably isn't the best idea for sound.
So with this point my choices really are the Apogee mini DAC, the HD 25 converted, and possibly the Hilo. Of those 3 the Hegel is my choice for SQ.