2. amps-preamps
  3. 1215914469

Pass Labs amps. Help me choose.

Speakers: Focal JM Labs Electra 1037BE
Room: 15 x 20 x 10 (w x d x h)
Listening Volume: typically 70 - 80 db at listening position. occasionally peaks at 90 db with symphonies (Mahler, Tchaikovsky). Rarely if ever above 100 db.

First a little background. I had an opportunity to audition X-150.5 at home, and I instantly fell in love. I have a stereo + multi channel music system, and I need five channels of amplification. I have immediately acquired X-3 for center and rears, and have been looking to get X-150.5 or X-250.5. In the mean times I was using X-3 for fronts and center duties. I had B&W Nautilus 804 speakers back then.

Fast forward a few months, I have replaced B&W with Focal Electra 1037BE. Focals are wonderful speakers, but it turned out they are a mismatch for X-3. When driven with X-3 the tonal balance is noticeably lean. X-3 couldn't control the bass and dynamics, and loud transient became muddy. Not a big deal, as my intention was to use X-3 for center and rear anyways, but I still needed amplification for the fronts. I've then acquired Levinson No 335 to drive Focals. With Levinson the bass control and dynamics are back.

Objectively, No 335 is an excellent amp and I could happily live with it for a while. However I am still partial to Pass Labs, and I would like to get a proper Pass amp for my speakers and compare against my Levinson. I do miss the musicality and the ease of flow with the previous set up with Pass amp. The amps I'm currently considering are the following:

X-350.5
XA-100
XA-100.5

X-350.5 and XA-100 are within my budget. XA-100.5 is a somewhat more than I would be willing to spend on amps. But if it comes down to only XA-100.5, then I am willing to take a leap.

Obviously my primary concern is whether the amp can drive my 1037BE. They are not an easy load where the impedance swings from 3 ohm in low bass to 18 ohm in upper midrange. X-3, a sibling of X-150, had problems driving my speakers. Personally I would choose XA-100 if it doesn't show the problem X-3 did and can drive my speakers with correct tonal balance. I don't know if it can or can't. X-350.5 looks great too. Two concerns with X-350.5 is that I don't want to pay for the powers that I may never need (350W @ 8 Ohm and 700W @ 4 Ohm is really a lot of power), and I may later regret not getting the XA series and just "settle" with X series. Then XA-100.5 would probably be perfect, but with about 2x the cost.

That's where I'm at right now. If you own any of the models listed above please let me know what speakers it's driving, and how you like / dislike about your amp. Thanks,

jlee
jylee
dpac996's avatar
dpac996
714 posts
 
Jylee,
The impedance is frequency dependent. Which of course is music dependent. Given your favor of classical (and not pop or rap with high rms (average) energies of 30-40 hz) and the fact that we are talking about Pass amps (very stout) the recommendation still stands that the XA60.5 would be more than enough power for your application.
3 ohms is not a big deal; it's not like its the average. In fact the average is higher than 8 ohms. But they have to dial it in to an industry standard for marketing. Again, the key is (mainly) the higher than market average sensitivity and relatively benign impedance curve.

The only TRUE way to know is to buy the amps and see if you have a match in your system (acoustic space), but I would bet real money they have enough juice to satisfy your listening habits.
Post removed 
dpac996's avatar
dpac996
714 posts
 
Tvad
anything above 2 to 3 ohms with moderate phase angle IS benign to most modern ss high end amps, especially Pass. 19, 30, 150, 500 ohms matters even less. What we are discussing is current delivery. The Pass, as you mentioned is very capable. Thiel CS3.6s OTOH are proven tough loads (large reactive phase angle combined with impedance that dips in the 2 ohm range across large swath of lower frequencies) and are not that sensitive.
I stand my by statement. The 3-19 means little in the context of 93 dB/1Wm. Believe what you want, it's a free country.
Post removed 
dpac996's avatar
dpac996
714 posts
 
Tvad: I see. In that case a really competent tube amp like VTL or some ARCs and BATs might be a good fit too. This is one of those thorny issues that, sadly is marginalized by marketing to a single value (8 ohms/4 ohm). There is a member (I think oneobgyn) who has found amazing synergy and drive with an 18 wpc LAMM tube amp into some higher end Wilson speakers. This flys in the face of conventional wisdom, but is another case illustrating that for real answers we must try something with our own equipment.

My colors ran out of gas many clicks back. I'm exhausted.
More to discover