2. amps-preamps
  3. 129597-97719

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
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. 
karl_desch's avatar
karl_desch
207 posts
 
Why did I type Mogami?  I meant Canare star quad XLR.
hardball OP
9 posts
 
Thank you ALL very kindly!

Sorry to bug you again... Could somebody please comment on the XA30.5 headroom? 

From Stereophile's measurements: "Ostensibly a 30Wpc class-A design, its measured performance reveals that it can actually deliver clipping-free peaks 6dB higher in power..."

Not sure if I understand this correctly, but does it mean the XA30.5 has a headroom of 6dB?! For example, MC452 has 1.8dB only...

@jaybe noted "I have this amp, wonderful, hope to soon move to the .8 series." EXTREMELY important: could you please give me your considerations? XA30.5 - Stereophile Recommended in 2015...

@karl_desch Are you referring to Canare L-4E6S Star Quad Balanced Audio Cable, please? I can order this XLR from Blue Jeans Cable.

Do I understand correctly you guys believe the XA30.5' stock power cable is adequate?

And last but not least... What do you guys believe would be a fair price for XA30.5 in excellent condition nowdays?


cal3713's avatar
cal3713
388 posts
 
Before changing speakers to a high efficiency design, I had Thiels and an XA-30.5.  I loved the combination. Left the amp on 24 hrs a day and the room would only get hot if I was really pushing the amp for long periods.  At idle or casual listening it was just warm.  I also did not notice huge electricity bills (gas and electric around $90 for a three bedroom house with two people).  
More to discover