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Pass Labs XA30.5 in my system?

Dear Audiophiles!

I am looking for a solid-state class A power amplifier with balanced circuit topology to replace Acurus in my modest Hi-Fi setup:
 
Mac mini (USB3 output) ->
Singxer SU-1 ->
Yggdrasil DAC (AES/EBU XLR input) ->
Primare PRE30 preamplifier (AES/EBU XLR input) ->
Acurus A250 power amplifier (RCA input) ->
Monitor Audio RS-6
 
I am currently considering Pass Labs XA30.5 and am wondering if it will “work nicely” with my upstream and downstream components.

Any info/advice is very much appreciated. Please chime in!

Please see the specs below for your consideration.

Pass Labs XA30.5

Type: Solid-state stereo amplifier
Power Output: 30 wpc into 8 Ohm, 60 wpc into 4 Ohm (both 14.8dbW)
Power Consumption (Watts): 238
Temperature (deg C.): 53
Voltage Gain: 26 dB
Input Sensitivity: 0.77 V at 26db gain
Frequency Response: 1.5Hz–100kHz, –3db at 1.5Hz, –2db at 100kHz
Signal/noise: 150db at full power (I cannot believe this is not a misprint!)
Distortion: 0.01% at 3 watts, 0.1% at 30 watts (measured at 1 kHz)
Input Impedance: 30 kOhm balanced, 15 kOhm unbalanced
Damping Factor: 150 for an 8 Ohm nominal load
Maximum Output Current: 20 Ampere
Maximum Output Voltage: ±35 Volts
Output Noise: 150 microvolt unweighted 20 Hz - 20 kHz
DC Offset: <50 mV
Slew rate: ±50 V/µs
Dimensions: 19" (485mm) W by 7" (180mm) H by 19" (485mm) D
Weight: 62 lbs (28kg)
Shipping weight: 75 lbs (34kg)

Primare PRE30 Preamplifier

Balanced inputs          560mV
Line inputs                   280mV
Sensitivity adjustment    -20dB to +20dB
Tape outputs               280mV
Gain                            16dB
Frequency response    DC to 100kHz ± 0.1dB
THD                             <0.01%
Signal-to-noise ratio    -118dB
Crosstalk                      -113dB
Mains                            100/115/230V
Dimensions (WxDxH)    430 x 410 x 100mm
Weight                           9.5kg

Monitor Audio RS6

Frequency Response: 38 Hz - 30 KHz
Sensitivity (1W@1M):   91 dB
Nominal Impedance:     6 Ohms
Power Handling (RMS): 120 W
Recommended Amplifier Requirements (RMS): 40 - 120 W
Tweeter Crossover Frequency: 3 KHz
Drive Unit Compliment: 1 x 6” C-CAM® Bass, 1 x 6” C-CAM® Bass Mid-range. 1 x 1” gold dome C-CAM® tweeter.
Cabinet Design: Balanced velocity twin reflex ported
Product External Dimensions: (H x W x D) 850 x 185 x 250 mm
Plinth Dimensions: (H x W x D): 25 x 255 x 305 mm
Individual Weight: 18 Kg

N.B. Impedance varies with frequency and goes to as low as 4 Ohms and as high as 16 Ohms. And, most importantly,“real” sensitivity is much lower than “nominal”: 87.40dB (averaged 300Hz-3kHz, 2.83V/1m)!
Measurements taken in the anechoic chamber at Canada's National Research Council can be found through this link:
http://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=1221:nrc-measu...

hardball
hardball OP
9 posts
 
Thank you very much @cal3713 ! For me it is a huge difference: $3300 at Reno and about $2700 at US Audio Mart. My problem is that not many sellers are willing to ship to Canada...

Could you please give me your suggestions on solid-state  power amplifiers with balanced circuit topology biased in such way that they do operate in class A for the first 20W - 30W? Oh, and I would prefer to stay up to 3K used...

I was considering the Son of Ampzilla II stereo power amplifier (http://www.sst.audio/son-of-ampzilla), but in this design Class A bias extends to 10W only (http://www.6moons.com/audioreviews2/sst/2.html).
wolf_garcia
6,625 posts
 
I recently switched to the Efficient Speaker/Small Tube Amp Camp (ESSTAC). This is after decades of having fun with various SS and tube amps (I also owned an Acurus A250 years ago that sounded fine but had to be sent back to Mondial a couple of times for repair…annoying). I recently bought a pair of Sonist Recital 3 speakers (93db seems like enough efficiency for my purposes) and a Dennis Had "Inspire" SEP "Fire Bottle" amp with 12 massive watts per side (massive…trust me). By far the best sounding rig I’ve owned, and FAR less expensive than one might expect for hifi astonishment.
hardball OP
9 posts
 
Thank you very kindly @wolf_garcia !

My "cave" is only about 14x14x9 and I am concerned about it being overheated. Hence, requirement for a SS amp.
Is there such a thing as fully balanced Tube power amp within my price range? How often is it required to change tubes, please? I would guess, every 2000 - 3000 hours or so? Some of them are made in Russia. How is it even possible to find those in case of necessity?! 

Found one XA30.5 for sale at 3.3K (ouch...). What questions regarding this amp would you recommend me to ask the seller, please? I have no experience with class A gear...
wolf_garcia
6,625 posts
 
Tubes can last years (preamp tubes the longest, power tubes less so but no biggie as switching them out is interesting), there are tons of them available (remember…millions of guitar amps out there use FAR more tubes than hifi ever will), and a tube amp isn't necessarily much less hot that a class A SS amp. One benefit of the small amp I mentioned is the fact that it has 4 under stressed tubes, as opposed to 8 in the amp it replaced. 
hardball OP
9 posts
 
Thank you very kindly @wolf_garcia !

This is totally unexpected: "... millions of guitar amps out there use FAR more tubes than hifi ever will..."! I must confess I had no idea tubes are still in use by musicians, i.e. professionals who can obviously hear the difference and did choose tube-based over SS gear! This is truly astonishing...

Could you please give me a few examples of tube-based power amps working in class A to drive my Monitor Audio RS6? Are they also end-to-end balanced?

If I go tubes with power amp, should I also switch to a tubed preamp as well?

Frankly, I still cannot understand how it is even possible a tube amp dissipating less heat than an SS-only design...

Checked your Sonist Recital 3 speakers: they are work of art!
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