12AU7 are my favorites as well.

I've had several email exchanges with Feliks, Lukasz in particular. Most of them were responded to in less than 24 hours. There was only one that was never responded to that I assume was lost in the email shuffle because I waited 3 weeks and wrote Lukasz again. I received an immediate response.

I agree that it might be impossible to eliminate all noise with a powerful tube amp like the Envy when using very sensitive headphones. It does sound like the OP is experiencing higher than normal noise. When I first described my problem, a lot of people said that my noise was so low that it...

I sent you a PM with contact info for Upscale Audio.

I could hear external transformer noise if my head was close to the power transformer if I really listened for it. Upscale Audio told e that it could be normal but they could put it on a bench to see how loud it was with the scope. I couldn't hear the hum when playing music using any headphones...

I wasn't tracking that Upscale is no longer a U.S. distributor as I just had my power transformer replaced less than 30 days ago. I'm not an expert on tube amps so you might be right regarding the power transformer, however, the power transformer fixed my problem and Upscale Audio told me that...

Sorry to hear about the troubles that you are experiencing. If bought new, these issues should be fixed under warranty. I understand that after paying so much for the amp that you want to move on.

The Yggy OG A2 with Unison USB is the latest version of the OG. These aren't the modular versions but if you're good with electronics you might still be able to upgrade to Unison USB by purchasing parts through Schiit. Not sure if they still have A2 boards. If you're not good with electronics...

The retailer is full of crap. As I and one other user have demonstrated, swapping the power transformer will more than likely eliminate the hum. If you are in the U.S., reach out to Upscale Audio directly and they will take care of you. You will have to pay for shipping to them which is...

Most users experience no hum at all with the Envy and although there have been users such as myself who have experienced hum, the number is probably in line with the variance of any company regardless of price. I have no hum on any gain with Susvara. I have no hum on LO with any headphones. I...

Envy and Susvara is an excellent pairing and one of the best I've heard. It gets better after rolling tubes. I particularly like the combination when paired with an R2R DAC. There was someone on a Facebook forum who had heard Susvara on an EF1000 and Envy and he said that the EF1000/Susvara...

I think the power tubes will be more likely to fix the issue if it's tube related. Because driver tubes are cheaper, it's worth a try to go that route first, but power tubes are more than likely to fix it. If it's not tube related, neither will fix it. Some users have reported that dirty power...

Hopefully the store you got it from can get it sorted for you. I agree that for the price of the amp, this shouldn't be an issue, but it seems that there are more people that have not experienced issues than there are who have. I guess we were the unlucky ones. My issue wasn't that bad to begin...

Your hum issue sounds a little bit different than the one I had. I could slightly hear the power transformer hum without headphones if my ear was close to the transformer. When using low sensitivity headphones like Susvara, I could not hear the hum through headphones with or without music even...

From my experience, I don't see the A2 as being up-front or close to the stage. I'm sure this may be system dependent but with the A2 I get a lot of depth. When using a tube amp, I can change the staging depending on my tube choice. Even with a SS amp, I get great depth from the OG A2 though.

Makes me wonder why the narrative changed all of a sudden. The Envy is a very good amp that they didn't give much credit. After a few people mention that they have never heard grain, the test unit may need more time on it, and several other reviewers who have reviewed both, clearly place Envy...

G73's are my favorite driver tubes as well. 1960s Mullard ECC82's are next with RCA red base being very close to the 12AU7 driver tubes and my best 6SN7-like driver tubes.

I tend to enjoy Koji's reviews but like I mentioned on a Facebook post today, I respect his testing process and the high end gear that he's had the opportunity to review, but his opinion and that of his team is still subjective even if he feels his testing is objective. Just because him and the...

Susvara is very insensitive so you're not likely to hear any noise regardless of gain setting. Now that I received my Envy back from repair, I hear the slightest noise on HI gain and nothing on MED and LO with Sennheisers. The amp is totally silent now externally.

Cable Matters Premium 2 pack XLR cables. They are OFC cables and have good reviews but are advertised as microphone and speaker cables. That could be why there was improvement when I replaced them.

I use the PYST Snake Oil XLR cables that Schiit sells. Found them to be a significant improvement over the previous Amazon cables that I was using although they're not very expensive. I believe in quality cables but it's not rocket science and you don't have to break the bank to get good sound...

I've had both and there was no difference in sound. The black glass were made a little bit later, I think in the 60s and were used to reduce the light signature for military application. Other than that, everything is mostly the same.

The other thing to remember is that system synergy matters more than how much something costs. A $20K system that has synergy will sound better than a $100K system with no synergy. One can use an $18K DAC that sounds great with one amp and sound terrible with another amp. A $3K DAC might be...

Humming should not occur using RCA or XLR. I have not experienced humming using either.

Thank you