Adcom GFP-750 Modfication Question


Has anyone had their Adcom GFP-750 preamp modified or heard one thats been modified by Stan Warren at Supermods in Eugene,Oregon?
If so, does it make a big improvement?If so, in what ways?
What all does he do to it? Or, am I better off keeping it stock from the factory?
daltonlanny
Black Gate caps give a warm liquidy feel to the midrange from the research Ive done and heard. Downside is break-in time. The consensus is it takes about 500-1000 hours for break-in. $150 may be worth the price if you use the Active Stage. I never needed to when I owned this unit awhile back, I was always in passive mode using all xlr's. ANd as they say, the best pre-amp is no preamp, and the closest to no preamp is a simple passive resistor with minimal traces design of Nelson Pass.
Daltonlanny,
Ritteri has succintly and accurately described the added "warm liquidity" to the midrange. Further, I heard less grain throughout, which resulted in a smoother, more relaxed presentation, especially top-end, with no loss of detail. While the Black Gates did take some time to break in, I started hearing obvious improvement within a week, and not much more improvement after two to three weeks--though I had my CD player running through it during much of this time, I would at least halve the break-in time Ritteri suggested to 250-500 hours. Yes, if I wasn't clear before: the $150, trouble, and wait was worth it. (Stan also did a great job handling the unit, leaving no external trace.) In my experience and for my listening preferences, there was "gain" and almost no loss in using the Black Gate active mode as compared to the renowned passive mode.
Michael Percy Audio sells Black Gates. If all you have to do is swap out cap's maybe you could do it yourself and not have to ship out the pre.
FWIW, I asked Adcom about swapping out components and they told me they use high quality components throughout and there was no need to upgrade anything.
Improvements are as described by Lmack and Ritteri. I would not recommend just swapping out the caps yourself since the values used by Stan are not exactly the same as used by the mfg. However, the improvements are noticible immediately and the unit will continue to improve. I almost always used it in active mode, which I believed provided more lifelike dynamics. The preamp was bettered overall (in my system) by a Muse Model 3 Signature. - Good luck.
A very important question: Is there any way the sonic performance of the active stage of the Adcom GFP-750 could be DOWNGRADED by having the caps changed to Black Gates, compared to stock? My system sort of sounds dark and warm to begin with.Would there be too much warmth and an even darker sound by going with the Black Gates? Is there any improvements to soundstaging, imaging, and/or image focus by going to Black Gates? What exactly happens to the top-end when going to the Black Gates? Does it stay the same, open up more, gain detail, or does it sort of darken and become more laid-back? Your detailed input would be greatly appreciated.