Pass labs amp choice for cls - what would you do?

After much reading and soul searching I have decided to upgrade the amp on my CLS speakers. I can buy a used X350.5 (current generation) or a pair of X600 mono blocks (previous generation - can't afford the X600.5) for a similar price. Is the .5 model change significant? There is no way that I can audition/compare them on my system, so I will have to take a leap of faith. I know I can't go wrong, but what would you do? And what pre-amps should I be looking at?

dchazen said:

After much reading and soul searching I have decided to upgrade the amp on my CLS speakers. I can buy a used X350.5 (current generation) or a pair of X600 mono blocks (previous generation - can't afford the X600.5) for a similar price. Is the .5 model change significant? There is no way that I can audition/compare them on my system, so I will have to take a leap of faith. I know I can't go wrong, but what would you do? And what pre-amps should I be looking at?

Click to expand...

I have had considerable experience with Pass amplifiers and the M-L ESLs although it has been on either their hybrids (Ascent, Summit) and most recently the full range CLX. I don't know how big your room is or how far you sit from your speakers but having recently owned a X350.5 (traded for XA100.5 monoblocs), this amp was an excellent match for all of the speakers that I heard. It has plenty of power and runs the first 40 Watts in Class A.
While the X600s are good amps, you probably will not need that much power and they do not sound as good as the 0.5 series. So if those are your choices, you might be better off with the stereo amp. BTW, these amps are very large and very heavy. They do put out some heat as well. You might consider investigating the stock at Reno HiFi. They always have demo equipment and will allow you a 30-day no-risk home audition. You pay for shipping of course.
As for preamps, I have also used Pass preamps for two decades. The newer XP 10 or XP 20 are excellent matches for these amps. Dead quiet, good at detail retrieval and don't get in the way of the source. They also allow the amps to be used as balanced units which is the way that they sound best.
Hope this helps. Good Luck!

Thanks for the comments. You got me thinking about the XA100.5 I would appreciate hearing your thoughts about the X350.5 versus the XA100.5 on a CLS.

dchazen said:

Thanks for the comments. You got me thinking about the XA100.5 I would appreciate hearing your thoughts about the X350.5 versus the XA100.5 on a CLS.

Click to expand...

I don't have the ability to make that comparison. However, a few points to consider. The CLS's have performed very favorably with amplifiers that are tubed or have tube-like qualities. The XA series is the most tube like solid state amplifiers that I have ever heard but without the noise or sonic blur that many tube amps have. The X series is very detailed but could highlight the high frequency issues that CLS's have making them sound edgy.
You could demo an XA series amp at home and make the decision yourself if you deal with a dealer that will allow you to do that. Probably the best way to make that decision since your ears will be your guide.

From everything I have read and what you have said, the XA100.5 is the way to go. It is a no compromise Class A power amp that should have a tremendous synergy with the CLS. Auditions are not really possible. Local dealers don't stock the amps. The cost of shipping and restocking fees from distant dealers is prohibitive. Besides, the XA100.5 is relatively expensive used as compared to the X350.5 (percentage off list price). So having decided on the amp I want, and not wanting to bust the budget, I am going to wait for XA100.5 to age a bit and come down in price on the used market. If you ever decide to sell your amps give me a shout. Thanks.