XP-25 phono preamplifier review.

Category: Preamps


I've grown to really like my “old” vinyl's sound and the quality of the sound. A lot of this is the phono cartridge, of course, but a lot is also the ability to get the most out of the cartridge, especially with low output MC designs. I can't really extract one from the other.

I've use many MC cartridges and head amplifiers over the years and they are not created equal. My current XP-30 and CLX speakers definitely said that my Sim Audio MOON LP-5.3 could be well exceeded with the right equipment. I have been using a very good Austin Audio Works Black Swan (my name) prototype unit that is amazingly good for the intended price, which is well South of the XP-25. To better asses the level of refinement of the AAW unit, I decided to upgrade to the XP-25 for developmental and support to Austin Audio Works and Belden ICONOCLAST(TM) cable developments.

The XP-25 is many times over called a “reference” level unit, this I've read. As good as the XP-30 is, I ordered the unit sight unseen and sound unheard. It arrived in a few weeks in a BIG box and is a two unit affair that is pretty darn heavy. The power supply is from the XP-20 preamplifier and is well overkill (or is it!) for the mission. The initial power-up did encounter a few gremlins.

The first issue was easy to solve, I had way too low an output on the volume, at 80 units to get about an 80 dB playback. I didn't mess around too much and quickly decided to remove the unit and go inside the control module and set the gain to one of three settings. It comes at the LOWEST setting, which to me seems mighty low. OK, there, that's fixed. Now I have adequate volume around 60-65 on the volume knob with CD input.

The second issue was one of those things with audio devices, static tests do NOT correlate with your ears. We all know that but it still kicks us around once in awhile. The right channel was a full 3 dB louder than the left. No matter what I did, it persisted. I tracked it down to the XP-25 for sure. Oh it sounded fantastic, but leaned on it's good leg. Here is where Pass Labs is such an excellent company to deal with. Kent English walked me through all the typical stuff to make sure it was the unit, and then sent and RMA out to find the issue. Never had this happened before. I love being first...sometimes.

The problem picked on Pass Labs as the static measurement showed dead nuts gain linearity, where it was tested from in the circuit. But, it turns out if the unit was tested dynamically, the problem found to be a ultra high grade audio cap that was uncharacteristically not an ultra grade capacitor in real terms of use. A quick replacement of a once in a million bad caps and we are off to the races. Now the sound stage was dead nuts centered upon arrival.

The last set-up issue isn't the unit per say, but the HUGE issue of 76 dB of gain needed for my Benz RUBY Z MC cartridge. True, the unit are shown shown one unit on top of the other, but this isn't going to be how you likely use it to reduce the noise floor to a minimum. Stacked, I had 120 Hz spurious noise through the right speaker more than the left. The electromagnetic field in the power supply was “under” the right channel in the upper control module. With such high gain, I had too much noise at normal listening levels.

The umbilical cord from the control module and power supply is several feet long, about five feet or so. OK, lets get a best case situation going. I grabbed an AC extension cord and pulled the power supply out of my rack and set it on the floor as far out into the room as it will go. DEAD quiet up to 80 or more on the XP-30 volume knob, or about the SPL of a freight train going through my sound room if you played music at that setting.

I moved the power unit towards the control module and turned it in all manner of directions till I figured out the angle and distance needed to get the unit into the rack with the lowest noise possible. It like to be VERTICAL besides the stack of equipment while the control module is on the very top of the rack horizontal. Be ready to set the power module at a distance and orientation to get the noise floor as low as possible. The umbilical is long for a reason. The unit is DEAD quiet set-up properly, so I can't get too upset that they don't like to be stacked.

The power supply is sort of like an unwanted but necessary evil, which is why Pass Labs kicked it out of bed in the XP-25 anyway. They are too noisy to get the best out of extreme gain amplifier.

The power unit is a necessary evil to place properly, but ejecting that pretty power box is an easy deficiency to accept and just as easy to do. Don't let the issue of noise fool you, it's a set-up procedure to get the high-gain control box as optimized as it is and not really a fault. Every unit I've used touted to be “extreme” performance units share noise issues if too close to many offending “things”. And some far harder to fix than the XP-25 was. Some were never fixed. To me the XP-25 sensitivity is a none issue as it's a drag and drop thing with the power brick.

What's it sound like? More like NOTHING than any unit I've ever used. Many keep saying Pass gear is “warm” but I fully disagree. A warm preamplifier and a warm phono amplifier and a warm power amplifier equals way TOO warm. The XP-30 and the XP-25 maintain a high degree of clarity and focus through what some say is a “warm” Sim Audio MOON W-8 amplifier. None of these three components are warm in my book, but capture the proper lower register tonality extremely well.

The RUBY Z is indeed a warmer and smoother sound than some unnaturally, but fun, lively cartridges I've used; SUMIKO Blackbird, AccuPhase AC-2. The XP-25 doesn't add a drop more warmth or ZIP, allowing this slight smoothness to be just that, slight. The MOON LP-5.3 was far too “warm” especially with the RUBY Z. This isn't about the cartridge, but to point out that the XP-25 gets out of the way enough to really tell what your cartridge is actually doing.

A reference level unit should excel at all frequencies, and allow the most to be EASILY retrieved from you cartridge...so you actually DO IT! The XP-25 doesn't disappoint. Quick loadings are about a second away on the front panel. The RUBY Z quickly fell into 100 pF/foot and 1K-ohm loading. The capacitance didn't seem to do much at all, but the resistive loading sure does. Too low resistance and the image falls way too far into the sound stage and becomes too tightly focused, a ship in a bottle, a very nice looking SMALL ship. Listen as you go and move up the resistive scale pulls the image BETWEEN the speakers, sets a proper width and sets the frequency balance to a more neutral sound. So much for the RUBY Z, the fact is that this type of tuning is SO EASY with the XP-25.

The most striking thing about the XP-25 is the bass resolution, power is there as most units get that, but the ability to hear WHAT the BASS is, and not just feel the power is extraordinary. Tonality is well fleshed out in the lower registers without being “warm”. To me warm is an enveloping fog of bass indecision that simply fills the room without a care as to WHAT the bass is, it just is. It can be a wet gooey swamp or a thin tight dry desert. But the ability to IDENTIFY the bass is MIA. The proper timber balance set an incredibly easy to listen to sound stage as you never have to process what the instruments should be. Same with the solid image stability of the XP-25. The mids and treble are excellent, and made even more impressive by the accurate lower registers.

The CLX are terribly fussy on bass resolution over power. They do one in spades over the other in moderation. Guess which is which! I have to work with the speaker's strengths of resolution tonality over power with the CLX and the XP-25 delivers. Yes, even with stereo BF-212 subs.

Some claim that even more premium units have a top end sparkle that exceeds the XP-25, but the CLX are no slouch on upper register transparency and this was certainly not evident to my ears. Possibly with softer speakers more sparkle might be needed, but at this level of refinement I'm not sure why we would use a speaker that needs goosing in the treble. A different sounding treble, but not enough? I think the comment was the tonality more than the “amount” of treble. The Pass Labs standard set by the XP-30 courses through the XP-25' veins, if not to say the XP-25 might be better, actually, than the XP-30 through CD's. Pass Gear is OPEN and naturally FAST sounding. I've said it about the XP-30, that the units track the music, not the other way around. They allow the signal to be more what it is, not what the circuit deficiencies “allow” it to be.

Mid range voices are in the room tangible events. No, they aren't movie set BIG or close miked sounding but “real flesh and blood” there in front of you. Listen to Bruce Cockburn, Tracy Chapman, Gordon Lightfoot or similar recordings and POW, you think, “so that's what he / she sounds like”. The naturalness is addicting as hell, too. You won't have any complaints breaking the unit in...which to me was a two day at most affair. Plug it in and let it sit a day and done.

Several records were used that I know are “right” sounding through the last 30 years or so. Peter Paul and Mary, and Jim Croce, which I ALWAYS use to set VTA as his voice is perfection for this task. I don't really spend too much time trying to fix funky recordings and listen for what they are. Chasing those weird mixes to some sort of accuracy is a never ending game of making other poor sources even worse. Get the right stuff right and move on with that's your anchor in my book. Set the midpoint right and let the recording move as they may from that. The RUBY Z is a VERY good anchor cartridge with excellent tonality and accurate transient response and weight across the board. The XP-25 lets ultra fine cartridges shine as it is all about nuances at this level of the game.

Comparatively listening the XP-25 to the Austin Audio works shows where 3.5X (ouch!) the price gets you, that last area of perfection in the lower registers, as well as the ability to load the unit to perfection for the cartridge. The AAW unit is a fixed load right now, but that will change in production. The AAW unit is FAR away better than my MOON LP-5.3, for instance, and everywhere, too. It is far closer to the XP-25 and a lovely sounding unit. But, the XP-25 sends a clear message, there will be no measured audible quarter where I am deficient by more than 10% of the total available! Yep, units at 3X the XP-25 price are reported to edge it it, but JUST. $30,000 is a lot of dough for an edge as thin as this.

If you have the space and desire to vault your phono to near state of the art at 1/3 the price ($10,600 isn't cheap, though), the XP-25 should be on your short list. But, to extract the XP-25's goodness you'll need a darn good cartridge,speaker system and cables. Be warned, the magic doesn't happen until the proper spell is cast across all you equipment. I REMOVED my Benz RUBY Z from my system as it wasn't meeting the “magic” with the MOON LP-5.3. The SUMIKO's lively nature sure did the trick but wasn't as real an image presentation as the XP-25 and RUBY Z. The AAW let the RUBY Z come through very, well, and the XP-25 yet some more again.

Audio can go too far into the resolution game and walk away from reality. You don't go through life ever increasing your eyes magnification of detail, but we seem to do this in audio, and to a fault. The XP-25 doesn't do this, but hits the nail of reality square on the head. There is the magic of tangible reality using this unit with a premium MC cartridge that is special indeed.