Halo JC-1, Part 2

The monoblocks are full broken-in now and I am in my new location, with a much larger room to audition them. I installed a single dedicated 20-amp circuit for all of the grounded equipment using 10-gauge copper ROMEX - almost 45 feet long. Ungrounded equipment uses another circuit. No ground-loops here - dead quiet. The amps are dead-quiet too, with one exception. When I tried to connect the home-theater to them (including CATV), I got a noisy 60Hz hum that got somewhat better when I used the ground-lift switches, but was still unacceptable. The interesting thing is that with my other amp, the CODA 10.5, the front channels are dead-quiet. Must be the difference in steady-state current that is being drawn by the JC-1's. In any case, I will need an isolator for the CATV ground if I am to use the JC-1's for home theater.

I finally replaced the stock PC's with my own Grand Slams in 3-foot lengths. This improved the detail quite a lot. The latest thing I tried was to change the pre to JC-1 IC's from SE to balanced. This made a significant difference in imaging, dynamics and detail. Particularly, the venue reflections are now very obvious. The system is now rivaling the very best I have heard, including the WAVAC/Ceramique system at Dave Robinson's (Positive-Feedback). The only weak-point is now the speakers, which I will be modding this summer. The system currently looks like this:

Source: Modified Sony DVP-S7700 transport
Source to DAC cable: Bitmeister Digital 0.5m
DAC: Modified Perpetual Technologies P-3A and P1A
DAC to Pre cable: Holophonic-PC 1m
Preamp: Highly modified Mark Levinson #38
Pre to amp cables: Holophonic-XPC 1m
amps: Parasound JC-1 monoblocks
amp to speaker cables: Clarity 7 6 footers
speakers: KEF 104/2

After playing a lot with different passive line-stages, my Proceed AVP and my hot-rodded Levinson #38, I have come to the conclusion that these amps are very sensitive to the pre that is driving them This is eluded-to in the various reviews from BFS, Stereophile and TAS. They really open-up and have great dynamics when driven from a low output-impedance pre, such as the ML #38. They are a bit flat and lifeless with passive pre's in comparison.

I did notice some changes with break-in, but nothing like what was written by Marty in BFS. After 2 weeks to a month, they sound perfect.

I am a very happy camper now and have no regrets about purchasing the JC-1's. Highly recommended.
next thing you gotta do is isolate 'em...:-)
Geoff, Parasound worried about SARS as they are made in Taiwan so they put a purple mask on each and every one :-) Yes, they are sensitive to what is under them and have had good luck with the Promethean base as well as three cones.....
If you've only got one twenty amp feeding both amps, you will end up choking them. You need a separate twenty for each amp.

Other than that, glad to see you are having a good experience with these amps. Now all you need to do is start throttling them hard and often : ) Sean
These sound cool- I wonder how they would compare to the big Sim Audio W-10 monoblocks...
Would be interesting to compare these traditional energy hungry room heaters with the similar power cool running Spectron Musician II.