Pass X150 test drive

Sonance'84

moe.ron
Subscriber
I brought it home for a "try before you buy" demo. I'd like to make this the anchor for a new system, one that would take a whole lot to beat, and make me stop searching for that last little bit of audio bliss (until I hit the lottery). Here's a couple quick pics...
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The Adcom GFP-750 is on loan as well, just so I didn't have to use my integrated amp's preouts. I'll probably tag my integrated in though, so I can use the phono section, which the Adcom lacks.

So far, I'm impressed. I'm using a high-pass crossover for my mains, so I doubt the amp leaves class A.
 
They're on my radar for sure. Have a Pass Labs Xono 2-chassis phono preamp and love it to death. The build quality is head and shoulders above any other gear I have.

Looking forward to your impressions !

jblnut
 
I enjoyed a Pass X-150 along with X-1 preamp for several years running Magnepan/subs. Both of the Pass Labs can be found used fairly reasonable these days, and generally give up very little to the newer models, subject to one’s own opinion of course!
 
Balanced or unbalanced...does it make a big difference?

I'm going to grab some xlr cables so I can try running balanced from the Adcom. Using single-ended inputs at the moment.
 
As always, the balanced/unbalanced thing can be open ended. I Used, and still do, DH Labs BL1 interconnects, I happened to own both balanced and unbalanced at the time I had my Pass gear. The main reason was my amp sat in between my Maggies, and the gear rack was about 13 feet away. For the fun of it, I tried both situations, same gear, same cabling other than connections. I could hear no differences. While it was fairly quick to change over between the pairs, who knows how much that space of time in between is enough to skew the testing.

My current gear was designed as balanced circuitry front to back. In these circumstances, I utilize balanced connections/cabling, and still use the same DH Labs. Again, can I hear the difference? Very subtle at best(Maybe I should be called old cloth ears...). If I was in an electrically noisy environment, and much longer cabling than my 16 footers, maybe it might be more apparent, or not....These days, I find myself not really caring, I am beyond all the foo and muss of it all and just get on with listening to my music. But I realize there are many that still enjoy these types of tests, or chin stroking etc. trying to figure it all out, and that is okay too! Go with what works and sounds best to your ears! Enjoy!
 
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Balanced or unbalanced...does it make a big difference?

Maybe. Your ears will decide.

You will have to remove the jumpers from the XLR inputs when you use those cables. The jumpers need to go back in when/if you go back to RCA. Make a note of what holes they go in so you can replace them correctly.
 
What about power cycling...do you let the amp & pre warm up a little before listening or leave powered on 24/7?

I don't think I noticed much difference between an hour warm-up or 48 hour warm up so far. It sounds great either way. I just wanted to make sure I'm listening to the amp at it's best while on this test drive. I appreciate all the replies.
 
On my X-150, I typically left it in standby until I wanted to listen, my preamp was left on all the time, other than storm season. It’s all what you are comfortable with and your ears.
 
I notice on my X250, that it takes about 1 hour for it to sound its best. You can actually hear it come into its full potential. Happens rather quickly when it does it. There's a thinness to the sound before the amp gets fully warmed up. Not bad, but just not a fully rounded sound. My pre-amp is turned off between sessions, but it has a circuit that keeps the tubes warm. Don't really understand this, but those of you that have had an Audible Illusions pre-amp will know what I mean. If I had the money, I would move up the Pass line. The X250 used is a great "bang for the dollar" point in the line.
 
Well, while looking at different preamps and their output impedance, I realized that the outboard hi-pass crossover I was using was the incorrect output impedance for my power amp. The x-over comes in 3 versions, to match input impedance for your power amp, later versions came with a switch to choose between the 3 settings.

The X150 is 22k ohms balanced, 11k ohms unbalanced (which I'm running). My x-over is optimized for amps with 30k-100k input R. Any preamp used with the X150 should have no more than 600R output as well, for best matching, which is exactly what the Adcom I'm borrowing has.

When I first hooked everything up last weekend, the amp sounded great, but I could tell something wasn't quite right. I had very thin sound. So, I removed the x-over last night and went preamp to amp direct...it sounds much better now. I guess I forgot about the x-over impedance in my excitement to hook up the amp.

Gonna keep demoing it this week. I really like what I hear though. I think my friend is a bit reluctant to sell it now though. :rolleyes:
 
Probably the only brand of amps that could make me give up my Krell. Having heard various of their amps now, I can honestly say that they are fantastic amps that one could live with for a long time. Plus while they can get warm, they don’t get as hot as the Krell amps do. That’s a real plus for me. I would say that finding a used Pass pre would really kick it up a notch. Enjoy the demo, hope you pull the trigger.
 
The heat of the amp is important for me as well, which was one of the reasons for getting rid of my Manley 75+75 tube amp last year. While nice in the winter (all of 4-5 months here), most of the year it's warm and hot amps just drive up my cooling bill.

I keep going back to my Musical Fidelity A300 integrated amp, which barely gets warm unless it's pushed hard. Now that it's recapped, it sounds even better too. I plan to keep it as a bedroom/backup amp, but I might just use it to fund a preamp to use with the X150. I'm kicking myself for selling my Forte 2 preamp last year as well, which I sold a day before I got a new job.

I recently sold my old truck and want to put the money into a nice piece of gear, to take me to the next level, and as an investment. My friend has had this X150 sitting idle for years now and it's always been in the back of my mind, knowing they're not cheap. I keep going back and forth whether is should put the money into the amp or speakers first. I know what speakers I want to end up with, just need to track them down. The preamp is the main ? in my quest, I've been doing a lot of reading though.
 
You have built quite a few systems at this point. Unless this amp is a buy it now or leave it proposition. Take your time and do it right the first time. Pass amps are neither rare or hard to source. They do tend to hold value very well and finding one for a steal is like catching lightning in a bottle. I believe one of the best Pass dealers is based in Vegas.
 
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