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...

Quad isn't going to put high-end tubes in a $1,599 amp.

Find a Phillips/Mullard rectifier (UK plant, late 1960's).... then look for Sophia Electric 6 SN and SL 7's. Forget tube rolling. Get the Sophias. Unless you want to buy my RCA's and Heintz & Kaufmans, and etc. Then, replace the fuse.

I've got a PA-One (Serial ......0002) and have done tons of tube rolling... RCA Red Base, Heintz-Kaufman, Sylvania, ADZAM, etc. Finally settled on Phillips/Mullard rectifier (square getter) and Sophia Electric for the SN 6's and 7's. Hi_Fi Tuning fuse and etc. Pushing HiFiMan HE-1000 V2's...

Also using a AudioQuest Edison power outlet (the receptacle in the wall).

I'm using an IsoTek Sirius power conditioner. Nice improvement.

If you want to play 'tube rolling' I have a collection I'm willing to part with. RCA Red-base, Heintz-Kaufman (essentially a red-base RCA... in fact they had a patent encroachment suit in 1942, I think), ADZAM (Mazda spelled backwards), Sylvania's , etc... Think the Adzam (or Sylvania) were...

One more trick to help the sound, and this one shouldn't cost you anything ! This often helps, particularly if you have an older home. Tighten all the wire connections at your power panel. Jacketed wires come into the panel, and the last half-inch or so is stripped and pinch-connected with a...

I found the Phillips/Mullard 6CA4 / EZ81 rectifier at a shop in California. They're $75 now. I bought four or five of them when they were $50... from the same shop. The price increase suggests they're becoming rare. https://www.upscaleaudio.com/products/philips-miniwatt-6ca4-ez81 "Philips...

One more thing... Although the Quad accepts XLR or balanced cabling, the internal circuitry isn't balanced, and I believe the Quad's XLR input is grounded. A friend had a major problem with this. He picked up a hum in his system when he used the Quad's balanced inputs. My integrated amp...

My Quad has a sticker above the on/off switch and tells voltage, fuse, etc. Mine is set-up for US power. MusicDirect had the fuse, but Amazon had it for a lower price. If you do some searching you can probably sink a couple hundred bucks in the fuse. As with any of this stuff, you'll need to...

Mine came set-up for USA power. Hey, there's another trick you can do for the Quad... I installed a HiFiTuning fuse. It was about $60 from Amazon. There's a little drawer on back of the Quad. Pull that out and swap fuses. I think there's a spare in there... which I thought was a pretty...

I didn't look at any other headphone amps. My soundshop guy saw and heard it at a CES convention and recommended it. I told him to get it. I had to wait a little while, but one day it arrived. A good friend had a top-of-the-line Sennheiser. I shared the Quad... installed in his system. He...

Just to tease you.... my Quad is serial number xxxxxx0002. Got it before there was an authorized US dealer.

I'm very critical of the spatial properties of music. What I was chasing, and I'm satisfied I've found it, is to have a private audition inside the sound studio. The rectifier was my first upgrade to the Quad. But the crowning moments were the Sophias and the HE-1000 V2. I recently added a...

Don't overlook the rectifier. Some folks say it has no effect... it does... big time. Tubes supplied with the Quad are low-end stuff. Also... although the Quad accepts XLR cabling, the internals are not truly balanced. I'm using Cardas Clear RCA into the box, and Cardas Clear Headphone out...

I went through about $2k in tubes before I landed on the Sophia. RCA Red Base are very nice, but the Sophias are beyond glorious. And they're current production. Go for the top grade. A shop in San Antonio got them for me for $95 each. My headphones... HiFiMan HE-1000 V2

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.

Jodet,   I got a Quad PA-One from Hi-End Theater and Audio, Plano, TX... hiend@flash.net   It is glorious.  I'm feeding it via AudioQuest XLR cabling from a Marantz UD-7007.  I read a few reviews about a weakness in midrange and bass.  Perhaps a little at first, but let the tubes burn in for...