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  1. #1

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    Default Pass Labs X1 Preamp vs. Adcom GFP-750 Preamp

    Have you ever met someone for the first time and it seemed like you had been friends forever? That is what it has seemed like since I first installed the Pass Labs X1 preampin my two channel system. I like Pass Laboratory's designs a lot. Their products are very similar to what I would design for myself if I ever took the time to do so.

    The UPS man dropped off my X1 on August 29, 2006. What a nice way to commemorate the 1st anniversary of Katrina's "visitation" upon our fair state. Now, I'll always have something positive to associate with that date.

    The X1 (MSRP $5900) replaced an Adcom GFP-750 (MSRP $1499) that I have used since 2001. See how long I have been saving up? When the GFP-750 was reviewed in Stereophile in March of 1999, the reviewer stated:

    "Actually, the preamplifier that most reminded me of the GFP-750 was the Mark Levinson No.380S, which costs $6495. The two had similarly open, grainless characters. In direct comparisons I had an extremely difficult time discerning differences between them—and that was a sighted comparison! Blindfold me and ask me to identify which one was playing and I'd probably have to flip a coin."

    I found the X1 and GFP-750 to sound remarkably similar, which is not surprising considering they have a shared lineage. The GFP-750 was designed by Nelson Pass of Pass Laboratories. The X1 was designed by Wayne Colburn of Pass Laboratories. They both are high current MOSFET designs utilizing a simple circuit topology. The feature set of both preamps is very similar. They differ widely in the quality of parts, case construction, and power supply design and construction. The X1 is a two chassis design (one each for the control unit and the power supply) which is constructed of solid milled aluminum panels. Even the remote control is constructed from a solid block of milled black anodized aluminum.

    Of course, the most important thing is the sound. While the X1 and GFP-750 sound similar, the X1 simply gives me lots more of everything I want: more low frequency slam, more clarity, more image solidity, a lower noise floor, and more, more, more realism. The images at the outer edges and rear of the soundstage had more "weight" and focus. The insertion of the X1 made it seem like I had added a subwoofer to augment the low frequency output of the SDA SRS 1.2TL's. On musical selections with a lot of low frequency content, the dishes in the kitchen cabinets are now rattling. They didn't rattle when playing the same music through the GFP-750. Source material was LP's and CD's.

    The question that comes to mind is whether the X1, which retails for 4X the cost of the Adcom, gives you 4X the performance. Well, considering that this is the first component that has repeatedly "surprised" me, I would have to say it is at least 5X as good as the Adcom. How was I "surprised"? By sounds jumping out of places where I had never heard them before. Switching back to the GFP-750 revealed that the sounds were always there, just not as noticeable. The Adcom is an excellent piece of gear considering its performance and price point and certainly has nothing to be ashamed of.

    The foregoing observations were made with my analog source consisting of a Yamaha PF-800 turntable with Music Hall Maestro cartidge and a digital source consisting of a modified Sony CDP-XA7ES CD player.

    However, like my dad always told me, "don't get hung up on one thing because there is always something better around the corner". We were discussing women at the time, but his advice applies to audio equipment as well.

    On September 5th, the UPS man dropped off my Cary CD 306 SACD player. I was actually going to get a Sony SCD-1 SACD player and modify it, until I noticed that owners of stock and modified SCD-1's were selling them after purchasing a Cary CD 306. So, I decided to get one...to...you know...see what all the intrigue and hoopla was about. The hoopla was well deserved. Until I stumbled upon the Cary CD 306, I really hadn't heard an SACD player that I was impressed with. Sure, the SACD players I had heard, including modified SCD-1's, sounded better than Redbook CD players, but not (at least, not to me) much, much better. I was motivated to get an SACD player more out of curiousity than a belief that I was going to get at least 2X better digital playback.

    Well, to put it mildly, the Cary CD 306 is spectacular. Whereas the Adcom GFP-750 was able to "hold its own" in some performance areas when compared to the Pass Labs X1, the Sony XA7ES was totally humiliated in every performance aspect by the Cary CD 306. Here is an analogy: The Sony's audio rendering was similar to watching an HDTV broadcast of a stage play. The Cary's audio rendering was similar to being in a front row seat in the theater at the actual performance. I was particularly impressed with the speed, accuracy, and impact of the Cary's bass reproduction. This player hits hard and fast whether playing CD's or SACD's.

    The Cary's upsampling capability even improves the sound and resolution of Redbook CD's. Although, I found that setting the upsampling rate above 192 kHz "hardened" the sound and diminished detail. The Cary also plays HDCD CD's (High Definition Compatible Digital Compact Discs), but the upsampled Redbook layer of HDCD CD's sounded better to me than the HDCD layer. The HDCD layer cannot be upsampled. Lots of audiophiles think the Cary CD 306 is an absolute bargain at an MSRP of $6000. Maybe. It certainly is a bargain at the prices they go for on the used market, providing you are in the right place at the right time that a rich audiophile is dumping his CD 306 so he can get one of the "truly high-end" SACD players costing >$10,000. CD 306's do not show up on the used market very often. It pays to be diligent and scrounge around for deals. I have found shopping for high demand audio gear to be excellent mental exercise. It can sometimes be as intense as hunting tigers at night. I'll do a more in-depth review of the Cary at a later date.

    By the way, the CD 306 is the first piece of audio gear to put me in the "dog house". It is unfortunate that some women just don't understand why you would want to stay inside all weekend (alone) with your sparkly new toy(s). I did warn her that I "might" be kind of, sort of, scarce during the month of September on account of the UPS man and FedEx man bringing me a few new audio components to evaluate. She thought I was kidding. She soon realized I was actually giving a considerate head's up so that she could make other social arrangements. I do not like being in the dog house, but man, I'm tellin' ya...this is worth it.:D Sure, I could invite her to the party, but she would provide an intolerable amount of distraction just by being in the room. I'll make it up later.;)

    Associated Equipment

    Pass Labs X1 Preamp
    Adcom GFA-750 Preamp
    Parasound JC 1 Mono Power Amps
    Sony CDP-XA7ES CD Player (modified)
    Yamaha PF-800 Turntable (modified)
    Yamaha MC-705 Moving Coil Cartridge
    Benz Micro L2 Wood Body Moving Coil Cartridge
    Music Hall Maestro Moving Coil Cartridge
    PS Audio GCPH Phono Preamp
    Polk Audio SDA SRS 1.2TL Speakers (modified)
    Signal Cable Silver Resolution XLR Interconnects
    Signal Cable Silver Resolution RCA Interconnect (turntable out)
    Monster Cable Z3 Reference Speaker Cables (No silver content, just high purity, well insulated copper)

    Source Material

    Mostly the same LP's and CD's that are listed in my other reviews and a few SACD's, most of which were SACD versions of LP's and CD's I already own. Maybe I'll provide more details after I have caught up on sleep a bit and after I have formulated my strategy for getting out of the dog house.
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    Last edited by DarqueKnight; 09-11-2006 at 04:29 AM. Reason: Because I am an engineer and engineers like to change things.

  2. #2

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    It's about damn time, excellent gear, have fun.

  3. #3

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    Quote Originally Posted by dorokusai
    It's about damn time...
    Hee...hee....that's the same thing the 1.2TL's said.:)

  4. #4

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    Very nice system. I am always impressed with the sound and build quality of Pass Labs gears.
    I am sorry, I have no opinion on the matter. I am sure you do. So, don't mind me, I just want to talk audio and pie.

  5. #5

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    NICE!! all the gear is and looks top notch.. very nice, now to go back and read your review. :)
    MY HT RIG:
    Sherwood p-965
    Sherwood sd871 dvd
    Rotel 1075 amp x5
    LSI15 mains
    LsiC center
    LSIfx surround backs
    Lsi7 side surrounds
    SVS pb12/plus2


    2 Channel Rig:

    nad 1020 Pre-amp
    Rotel 1080 stereo amp
    Polk sda 2B
    kenwood grunt Tuner
    realistic lab 450 TT
    Signal cable IC

  6. #6

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    Quote Originally Posted by DarqueKnight
    We were discussing women at the time, but his advice applies to audio equipment as well.

    I have found shopping for high demand audio gear to be excellent mental exercise. It can sometimes be as intense as hunting tigers at night.
    these are the reasons i love reading your reviews. :D congrats on the new equipment, looks like you have really stepped things up with this recent group of aquisitions!

  7. #7

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    Quote Originally Posted by dorokusai
    It's about damn time...
    Hee...hee....that's the same thing the 1.2TL's said.:)

  8. #8

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    'Atta boy!!!
    'Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

  9. #9

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    ....drool....nice, very nice. I've been a fan of Nelson Pass for along time. The 750 is no slouch but I'm not suprised the X1 beats it so handily, it should especially when the down stream components are on the same level. Great read and some very nice audio components.

    H9
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30; Eastern Electric Mini Max; Adcom GDA600; MIT S3/Z Pc; SDA 1C; Squeezebox; Tubes add soul!

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