I don't think noise generally is a problem with Demeter preamps, their primary intent was recording.
That was a headscratcher for me, too. I'd heard nothing but good things about Demeter bass preamps, and then I tried one and it was just a hissy thing with next to NO tone shaping abilities. Maybe someone counterfeited a batch when they first got big. That was bad problem with China for awhile, before Uli Behrigner showed them how to do it with US backing. That would also explain the 2 rack spaces. In the late 80's and early 90's, the right amount of time for them to have fanned out and disappeared into the woodwork and someone like me to run across one, China put out a massive amount of counterfeit US goods, especially electronics all types, tubes included, encouraged by the party leadership so that they could both perfect their abilities to copy and increase their own QC.
The tone knob on a junkiest passive bass you can think of had more range than that preamp did. The knobs also had no effect on the noise. I always chalked it up to a case of the emperor's new clothes and my taste for low end, but who knows, maybe amptech and myself both encountered fake Demeters. I remember the 2 rackspace thing specifically because I thought the lettering on the preamp belonged farther up on the face. Maybe it was made off of a template from the 1.5 ru model.
There's a trim pot between the 12AX7s to adjust output. That could affect s/n ratio if turned too far.
Those are metal film resistors and Wima caps, good stuff. The tubes themselves are Chinese 7025 "Silver Specials" that Lord Valve raved on about for years. They're a little bit noisier than old Western World stuff, but nothing to speak of in the right circuit, which is just about ANY that would work at all. The noise I'm talking about would have been unacceptable in any REAL studio, and the owner of the one where it lived probably knew the brand name and nothing more.
It was the era of the project studio, (anyone else JUST realize that that term is as antiquated as I just did?) brought to you courtesy of Greg Mackie, where for about $50k, you could get yourself a couple of ADATs, a Mackie mixer or one of their many QUALITY copycats (Soundtracks Topaz, Soundcraft Spirit, etc), a bunch of whatever leftover 80's rack gear floated your boat, and mix it all down to a crappy prosumer DAT tape recorder that ate more tapes than it ever played. It was one of those places, one of many studios that published gear lists like they were filling a tour rider. I'm sure the owner aquired it and probably never even used it. It was in a rack in the main room with a baby grand piano.
I helped wire that studio and never got paid a dime. The studio lasted for a few years until it became apparent that Knoxville was too close to Nashville for the kind of money the owner was charging for the expertise and talent that he did NOT have. He never set out to compete with the "big boys;" he was hoping to turn it into a writers' studio, but most independent songwriters either already had their own or were willing to pay the prices to get the service they wanted. I did get to see some neat stuff there and I learned some very valuable things, so it wasn't a total wash for me, but wiring an entire studio is a big job, and gas may have been less than $1 a gallon, but it wasn't free, and unlike much of the clientele/booking agents, I didn't take payment in the form of bj's. Yeah, that part was...creepy and NOT cool. Learning that gay fellatio was currency was not something I had ever endeavored to find out.
Demeter..yeah...that's what we were talking about.