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Pass Labs X-1 -VS- Adcom GFP-750 Preamp

This thread is for people who own, or have owned both the Pass Labs X-1 and the Adcom GFP-750 preamps.
I am curious because the circuitry in both preamps was more or less designed by Nelson Pass.
What all sonic advantages does the Pass Labs X-1 have over the Adcom GFP-750, top to bottom and everything in between, when using the Adcom in both its Active mode and in its passive mode?
Does the Adcom have ANY sonic advantages at all over the Pass, or only disadvantages?
Is the Pass X-1's sonic improvement small, moderate, big, or dramatic?
Finally to those or have heard, owned, or compared both:
What all sonic improvements does the Pass Labs X-1 offer over the Pass Labs X-2.5 preamp?
How noticable are the improvements?
Thanks in advance.
daltonlanny
6 responses Add your response
jayctoy's avatar
jayctoy
4,043 posts
 
Dont forget the GFP750 is a class A gear,I think Wes Philip
reviewed it.This preamp served me for 4 years.For
me ,its very musical.I have not heard the X1, If Stehno
said its better, then I agree.
johnny
5 posts
 
I auditioned a GFP 750 with my Aleph 5 and thought it was only fair. I purchased an ARC LS-15, which I very happy with.
daltonlanny OP
301 posts
 
Stehno,
If you will view my thread history, I never had a thread which asked for a comparison between the Adcom and the Pass Labs X-1. Maybe I had one for the Adcom vs the X-2.5?
I am using an Adcom GFP-750 modified by Stan Warren with Black Gate capacitors by a previous owner and was just wondering if the X-1 is a big enough step up to justify its considerably higher price.
Thanks,
Lanny
stehno
1,453 posts
 
DaltonLanny, this almost looks like one of your old threads from a few months ago. Hey, are you running reruns? :)

I've owned both the X-1 and X 2.5 and I would suggest that the X2.5 is about 98% the performance of the X-1. This is by no means meant to slam the X-1, but is more an accolade toward the X2.5. In all, I believe both Pass Labs units are excellent products sonically.

One note is that I always used my highly-rated Foundation Research passive and dedicated in-line power conditioner with both units. Therefore, it is entirely possible that any improvements with such line conditioning the separate power supply with the X-1 may be negligible at best.

-IMO
aaronm's avatar
aaronm
99 posts
 
After reading reviews of the Adcom, I had auditioned it in my home for an office system. While the Adcom might have been adequate for many people's office system, for me comparing the two was comical.

The Adcom had nowhere near the transparency of the Pass and the Adcom in active mode was much noisier. I had to use it in passive to get it to be as quiet as the Pass. As this was in my office and would be almost a nearfield listening set up, the noise level was more critical than usual.

If one can afford the X1, I would suggest it over the GFP.

Best Regards
cytocycle
1,043 posts
 
Both preamps prefer balanced interconnects.. The passive stage is better on the GFP750 than it's active stage, but not as good as a Placette Passive. I haven't compared it to Pass in person. I have compared it to a CJ Premier 14, Rowland Synergy IIi, Placette Active and all were superior... but the Rowland had the best Synergy in my system
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