"or make the hole larger" Thats exactly what I did. Initially to accomodate a 7AF7 tube + adaptor which worked great for a while, but then had a run of bad microphonics with the same tubes and am looking for alternatives as they seem to be too unreliable. In my madness I also experimented with...

General question. Does anyone have an opinion on tube rolling from the 5670/2C51 series of tubes Vs 12AU/T/X series with adaptor?. Not concerned about which model MHDT you have, just the tube itself. In general do you rate the 2C51/396A higher or lower than 12AU/T series purely in terms of SQ...

Yes, she does now & then LOL. When I play through loudspeakers she likes to adjust her position and stand dead centre in the sweet spot, instinctively knowing about the "stereo" effect.

Still here, with the cap mod & original amp. Enjoying it as much as first day. After trying a whole host of tubes (earlier in the thread) settled on the 14N7 as driver & the unbeatable 6BG6G coke bottle power tubes. Spacing very tight but works fine. Shame they changed the design, mine's a keeper.

The ones I ordered were from "vicaudio_1" on ebay. In hindsight 160mm was a bit too big 150mm would be better. No extra cost involved

Yes, those tubes are fine. You will need to go to e-bay & look up tube adaptors for 6BG6G. The G version tubes are worth seeking out over the GA type.

Sad, but nothing lasts forever. Don't know but looks like the replacement is this with usb & some obscure 7 & 9 pin tubes: https://www.aliexpress.com/item/GD-PARTS-Brand-New-APPJ-Mini-Vintage-6J4-6P14-Tube-Amplifier-Smart-Desktop-Wifi-SD-Card/32811062445.html Amazon & some dealers on e-bay...

There is a limit to what you can run. Personally I would not go over 0.9A current draw. That still leaves a lot of choices, 6L6G or 6BG6G for example. Seriously you would not want to go bigger than that, not practical,the amplifier is the limiting factor.

I am a big fan of NOS Mullard tubes, but that one has a different pin out, do you have adaptors? If you go that way let us know how it compares.

14N7 @ $5.90ea 14AF7 @ $7.90ea https://www.tubesandmore.com/search/node/14n7?in=body 14F7 @ $4.25ea https://vacuumtubesinc.com/index.php/catalogsearch/result/?cat=17&q=14F7

That is the right adaptor but it looks ugly without the outer sleeve IMO. The same supplier will do one for you with a gold outer sleeve for an extra $5. (xulingmrs,china, on ebay) just ask him.

Personally I don't rate the 12AX7 very highly. I prefer the 12AT7 series, my preferred one is the little known 6211A which has a lower AF (price is cheap too, no hype attached). However after extensive trials & listening sessions I have found the 14 locktal series to be the best (adaptor...

It's already high end (with some mods/tube rolling), only those with upgraditus would want to move on to something else.

Since ESS have brought out new models they are selling the ESS RLM-713 Headphones now for $99. Snagged a pair, what a bargain.

No, this one here: https://www.ebay.com/itm/1pc-7N7-TO-6N3-5670-396A-Tube-converter-adapter/191646956894?hash=item2c9f0c7d5e:g:kMsAAOSwHnFVuMs9