QUAD PA-One Valve Headphone Amplifier and DAC
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freesole

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Has anyone had experience with this headamp that can compare to other tube amps out there?
 
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pablomen68

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Hi, the preamp output of the QUAD PA-ONE is fixed or variable? Can I switch between both? Also, do you know the output voltage of this? Maybe 2V., Thanks.
 
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sejsel

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Hi, the preamp output of the QUAD PA-ONE is fixed or variable? Can I switch between both? Also, do you know the output voltage of this? Maybe 2V., Thanks.
The preamp output of the Quad, upon testing that - first today (never thought I would use it as a preamp) is definitely variable, the output level increases with the turning of the volume knob. Out of precaution I disconnected the headphones while testing the pre-amp functionality.

Unfortunately, I do not know what the output voltage is. You should probably get in touch with Quad representatives (or the authorized retailer) for that detail.
 
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pablomen68

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The preamp output of the Quad, upon testing that - first today (never thought I would use it as a preamp) is definitely variable, the output level increases with the turning of the volume knob. Out of precaution I disconnected the headphones while testing the pre-amp functionality.

Unfortunately, I do not know what the output voltage is. You should probably get in touch with Quad representatives (or the authorized retailer) for that detail.
The preamp output of the Quad, upon testing that - first today (never thought I would use it as a preamp) is definitely variable, the output level increases with the turning of the volume knob. Out of precaution I disconnected the headphones while testing the pre-amp functionality.

Unfortunately, I do not know what the output voltage is. You should probably get in touch with Quad representatives (or the authorized retailer) for that detail.
Thank you very much.
 
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sejsel

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Bumping this thread, since I am reading the MAD EAR+ thread at the moment...

Quad Pa One has shown to be compatible (and does well) with a number of better headphones (including the Hifiman HE-1000 and Sennheiser HD800), so, a bit sad that it does not get more love and publicity. I guess being the British amp makes it less accessible and known in the US, perhaps that might be one of reasons.

I have used it with the Grado GS-1000 and AKG K701/2, and the synergy is really great, it drives both cans effortlessly, as it reportedly does the Sennheiser HD600 and 650.

Great holografic feeling (3D), authoritative, tons of detail... tubes that the amp is using are well known and easily accessible (6SN7, 6SL7 and EZ81 rectifier), the amp runs smooth and has the decent DAC (not the latest word, but still well implemented and more than adequate).
It can be used as a preamp as well...

The Quad has pre-released the successor, the Quad Pa One+, which uses the solid state rectification instead of tube, it has added the balanced output at the front, and the remote, other than that looks rather similar to the original model. Footprint is the same. It also has an improved DAC with better specs, that can be found online.

Great, very enjoyable headphone amp, IMO.
 
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dasmodul

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When you're ready to swap out the 6SL7 and 6SN7, go straight for Sophia tubes. I tried the RCA red-base route, and a bunch of others. The Sophias are awesome... and current production !! For the rectifier (EZ81) see if you can find an old UK made Phillips/Mullard.
The Sophia tubes look much bigger in pics. Will the grill cage fit with them installed? Can u share a photo of yours? Thx
 
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enduser

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The Sophia tubes look much bigger in pics. Will the grill cage fit with them installed? Can u share a photo of yours? Thx
Yes, I removed the grille. The amp comes with a t-handle screwdriver for removing the screws. Make sure the screwdriver is magnetized so you don't drop the screws. The Sophia tubes are a bit 'fatter' than other 6SL or SN 7's. The front pair (SL7's) have about a millimeter clearance between them . Sophia said this is no problem. I checked the Sophia site a while back and saw their new blue-glass versions (mine are the prior clear glass). You should perhaps check with Sophia the the new blue tubes are no fatter than the earlier clear ones.
 
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I just received a Quad PA-One + and listening to it currently.

It does sound absolutely fabulous on my HD800S. I'm feeding it via USB. Wonderfully spacious, very detailed, overall super pleasing.

There's one huge caveat though. It creates a hum in the left output when no music is playing. The hum is much lower in volume in the low impedance setting but very noticeable in the high setting.

Any chance this is going away after more hours of burn-in?
 
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I just received a Quad PA-One + and listening to it currently.

It does sound absolutely fabulous on my HD800S. I'm feeding it via USB. Wonderfully spacious, very detailed, overall super pleasing.

There's one huge caveat though. It creates a hum in the left output when no music is playing. The hum is much lower in volume in the low impedance setting but very noticeable in the high setting.

Any chance this is going away after more hours of burn-in?
Replace the stock tubes.
 
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Jodet

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pmpmpm

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I couldn't agree more. It sounds so incredibly amazing on my HD800S.

I just have to get rid of the humming somehow but I'm already in touch with the distributor regarding that. I guess the first step is replacing the tubes.
 
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Jodet

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I couldn't agree more. It sounds so incredibly amazing on my HD800S.

I just have to get rid of the humming somehow but I'm already in touch with the distributor regarding that. I guess the first step is replacing the tubes.
I had HD800S before I got the Arya's. Yes, the Quad and Sennheiser is a great match.
 
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When you're ready to swap out the 6SL7 and 6SN7, go straight for Sophia tubes. I tried the RCA red-base route, and a bunch of others. The Sophias are awesome... and current production !! For the rectifier (EZ81) see if you can find an old UK made Phillips/Mullard.

I'm also interested in seeing a pic of your amp with these tubes. I just picked up a PA-One+ and love it but intrigued by the Sophia's. How is the Bass over the stock tubes?
 
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