Preamp recomendation

I owned the GFP 750 and even after having the Black Gate cap upgrade performed, I couldn't get beyond the sorta bright and electronic Adcom sound. Replaced it with the MUSE unit mentioned earlier and found that to be much better sounding, and not bright. I am sure there are other good ones in the general price range too like the Classe mentioned or the Quicksilver tubed linestage.

I found the passive circuit on the Adcom to be dull and lifeless sounding. The best true (unbuffered)passive I have heard was a pair of Endler attenuators - but ergonomically they are not for everyone.

Mitch2/ghoeper

When you say that the gfp750 is bright, I take it that you were using it active. If so, that's why I recommend a passive unit. As for the dull sound running it passive, that's not always the case. The better the component, the better the output stage (usually). It's up to the amp in the source component to power the signal all the way to the amp. Your Cambridge 840 is a very well made CD player. Using that for your source, I can't see how you can go wrong with a passive. Also, you don't have to limit yourself to Adcom. The 750 is excellent but there are other companies that make passive preamps at a very reasonable prices, as well. I have used passives from Creek and Channel Islands with excellent results. I do prefer the Creek but both are great.

There are a variety of preamps that are called "passive." If the only criterion is no gain stage, then you have;

Discrete resistor units like Placette, Goldpoint, Endler and EVS attenuators, Khozmo and others (Luminous falls in this catagory but uses a pot),

Buffered passives such as First Watt B1 and McCormack TLC-1,

TVC preamps such as Music First, Django, Promitheus, Sonic Euphoria and others that have no active buffer or gain stage, but can often provide up to 6dB gain, and finally

hybrids such as the Pass L1 and McCormack VRE-1 that run buffered passive to a point and then can add up to 6dB gain.

I have a balanced Goldpoint passive and Endler attenuators here and they certainly sound different from each other, but both sound better than I remember from the GFP-750 - perhaps because the Goldpoint and Endler units use high quality discrete resistors and the Adcom uses an Alps pot, which IMO is way inferior to discrete resistors for attenuation.

The length and capacitance of the cable coming out of the passive also makes a big difference. In the cases of Endler and EVS, they offer the benefit of no exiting cable.

Stereophile said about the GFP-750: "In passive mode, the signal sees only input switching and the attenuator." This implies the passive mode is unbuffered and only sees the switches and the Alps pot. One issue with running the Adcom passive could be that since it is an active preamp, many will put it in their racks in a typical position where the exiting cables may be longer than if it were set up as a passive preamp where most would try and keep exiting cables as short as possible. That may be why I didn't like it, although I don't remember my cables being any longer than 1.5M in the set-up I had at the time I was using the Adcom. I remember it being somewhat bright and harsh in active mode, and less bright but also less dynamic and somewhat boring in passive mode.

Though there groups of committed activists and pacifists, I will say that there are folks using passive that have made that choice coming from very expensive active line stages in the mid to high 4 figure range - for some, not active can beat a passive in the right system context (source - passive - cables - amp). I am a fairly committed pacifists at this point, for the past 3 years or so.

I use the $450 Lightspeed Attenuator, which I prefer to any of the resistor/TVC/AVC passives I have also tried - limit? one input / one output.

Does Lightspeed make a mono model that plugs directly into the amp(s), like the Endler or EVS attenuators? In my limited experience, doing away with that output cable offers a significant sonic benefit when going passive.