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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 all very kindly!

I can only dream of Ayon Titan... @4hannons, would you agree XA30.5 (much less powerful...) is also capable of driving RS-6 nicely?

@steakster, do I understand you correctly there is no need in external forced air cooling (desk fan, e.g.) for XA30.5?

You also noted "There are many high quality Class A/B amps that don't generate as much heat.   They put out Class A for the first several watts - which is fine for most listening." Could you please give me a few examples of such balanced (end-to-end) power amps?

@timlub, could you please explain what you mean by "sliding bias Class A" in case of XA30.5? I think I have seen in one your posts the headroom of XA30.5 is 4dB. Could you please confirm if this is correct?

I believe we have a consensus XA30.5 will drive RS-6 comfortably. Are you guys in agreement PRE30 will also "work nicely" with XA30.5?

What balanced interconnects would you recommend for my setup, please?

Do you believe the stock power cable is adequate?

My budget is rather tight, hence all the bugging... Sorry guys and thank you!

timlub
1,649 posts
 
@timlub, could you please explain what you mean by "sliding bias Class A" in case of XA30.5? I think I have seen in one your posts the headroom of XA30.5 is 4dB. Could you please confirm if this is correct?

In a Pure Class A amplifier,  the outputs are at full throttle in idle... that is why the amps generate so much heat... In a sliding bias amplifier, the amps biased is raised so that the amp will output Class A longer,  the higher you raise the bias,  the more output in class A before switching to A/B...I know that other models of Pass do this,  one of the Alephs as well as the 30.8... I suspect it is the same on the 30.5. 
steakster
720 posts
 
Best to do a search in the Audiogon discussion archives. It has an enormous wealth of information. You will find all the answers to your questions and much more.
jaybe
386 posts
 
I have this amp, wonderful, hope to soon move to the .8 series.

Stereophile's measurements:
http://www.stereophile.com/content/pass-labs-xa305-power-amplifier-measurements#GIlEwhIt3MzcHIZ2.97
karl_desch's avatar
karl_desch
207 posts
 
The Pass Labs website does a great job of explaining their amplifier designs. If you wanted something that was less heat producing you could try their X series instead of the XA series. But I really don't think you have a problem with the heat from the XA 30.5. The efficiency of your speakers is not an issue with this amp nor are the lower  impedance dips across the frequencies.  
 Because your preamp is fully balanced you shouldn't  worry too much about quality of your balanced interconnects. I have compared A shorter run of Audioquest SKY to a long run (20ft) of regular old Mogami quad XLR microphone cable. The 60 dollar microphone cable was not inferior.  Other designers of balance amplifiers like Atma-sphere would agree that you shouldn't spending too much money on XLR cables  in a fully balanced connection. 
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