Can you link to these clips. I've always considered my HRM to be a very quiet amp and haen't ever noticed any more hiss when gain is cranked in clips then normal.

Don't get me wrong, I wasn't implying you were trashing the OTS and I don't think I answered your question.  I only stated that there is no more hiss in the OD channel than what should normally be expected in any tube amp when you raise the noise floor the level you do from the clean channel. If you have excessive hiss compared to other amps you have played or heard then I would say there is something wrong with your amp. The first and easiest place to look is the preamp tubes, especially V1 and V2. What are you using? The PI and power amp tubes can be an issue too, but not as much as a noisy preamp. I would try swapping some tubes.

I guess what I meant more than anything is a properly working OTS is a very quiet amp relative to the amount of gain you can achieve. And your question kind of threw me because I listened to probably a hundred clips when I was researching the buy and hiss was not something I remember being a factor. Nor to I hear it in any clips since. That's why I asked for any examples of what you're hearing.

After tubes is gets more complicated. Caps would be the next place to look.

Ah...ok, so this is a self built amp and not one already built by Ceriatone. First, congrats on building the amp.  (for some reason I assumed this was not a "kit build")

I had put the heater wires down like the pictures at first too, and then moved them above later. While is was mostly subtle it did seem to be an improvement on noise and furthermore, on tone.

Please don't take this the wrong way, but are you making a clear distintion between "hiss" and "hum"? The reason I ask is that the two usually have separate reasons for being excessive. I'm assuming that since you used the term "hiss" that's what you're talking about. The other reason I'm questioning is that things like moving heater wires will be a solution for getting rid of "hum". Once again don't get me wrong. I think moving the heaters and other lead dress issues is a great idea.

Speaking of lead dress, and other then the heaters, did you follow the wiring and lead dress closely to the pictures? I'm not sure how much you have read about Dumble style amps (or amps in general) but placement of the leads can have dramatic results in the tone and noise especially V1 & V2 wiring. Make sure the cathode wires as far from the heaters as possible. Pin 3 of V2 in particular.

Also, just to reitterate again. If it's just a higher "hiss" level when cranking the OD and otherwise the amp is performing great, preamp tubes can be the biggest culprit of this. Even if it's a tube brand that usually is not an issue, sometimes some individual tubes will have a poor S/N ratio.

Good Luck & keep us updated.

If the problem persists. A few clear, in focus, close-up photos of the guts can do wonders with more experienced builders spotting any problems areas.

Glad you're liking the amp and having fun learning and building. It's a cool thing for sure.

That's great. Yeah, I'm a stickler about noiese too. I have all my guitars shielded with copper foil also.

Speaking of a poor connection causing problems. When I was changing my heater wires, I left some solder flow down into V1's tube socket and just couldn't get it cleaned out to my satisfaction. I decided to change it for a new one. With all the poking and prodding that occurred, I weakened one of leads of the grid resistors to V1, but didn't realize how badly is was damaged. I had everything back together and there was a considerable amount of hum that wasn't there before. It took tapping on the resistor while the amp was on to realize it was something in that area. When I started to unsolder the part the lead finally broke and it was clear that this was an issue. Replaced with a new resistor and fired up the amp and quiet like before. I thought this a good illlustration of how unintened problems can occur.