How to turn on Unity Gain on Pre Amp

I misspoke on the subwoofer being one of the reasons why I need the preamp. It has been a while since I looked behind my gear and the REL subs are taped into the amp, only the grounds are on the preamp. So easily hooked up the Lumin direct taking the preamp out of the system and surprised to say it looks / sounds like a clear winner. Didn't want that to be the case as I love my tube preamp, paid a lot for it, and it has cool blue meters.... Still got some A/B testing to do, but I know my system and every audio adjective there is seems to be noticeably improved. Makes no sense to me??  I guess less is more.

So easily hooked up the Lumin direct taking the preamp out of the system and surprised to say it looks / sounds like a clear winner. Didn't want that to be the case as I love my tube preamp, paid a lot for it, and it has cool blue meters

Yeah, I worked for Magnolia for a short stint and they had the KEF Blades hooked up to Mac gear.  I’d heard the Blades at shows and they’re quite impressive.  Hooked up to tha Mac gear, it sounded mushy and slow and not at all like what I’d heard from the Blades at shows.  Bottom line, I think you’re hearing what I heard and that you’d prefer a more detailed and neutral sound.  But I also wouldn’t use the Lumin’s preamp.  Preamps are hugely important to a system’s sound and I’m sure you can find a better preamp than the one in the Lumin.  Look at brands like Pass Labs, Linear Tube Audio, Backert Labs, Audio Research, etc. and I think you’ll find Audio nirvana.   The Mac is veiled , cloudy, and obscures detail, which is obviously not the case using your Lumin preamp section.  Pretty blue meters aren’t worth un-involving sound, which I think is what you’ve now realized.  Hope this helps, and best of luck in your search. 

@soix 

The Lumin has no preamp. The LEEDH processor is a volume control only. And a damn good one. If a system is passive friendly, i.e. high efficiency speakers, high input impedance amp, robust source output, there's really not many preamps that can beat no preamp. But if you have a hard to drive SS amp with low input sensitivity, yes, you will need an active preamp. But even the best active preamp will not be needed in every system.

If a system is passive friendly, i.e. high efficiency speakers, high input impedance amp, robust source output, there’s really not many preamps that can beat no preamp.

I respectfully disagree. If it works out that way, fine. But many, many audiophiles find value in incorporating a quality preamp. I’d encourage @atmasphere to chime in here because, well, he’s a damn icon in this industry and a voice of reason here. IME, preamps are more consequential than amps, but yours is not my system or  my listening experience. My only message from personal experience, do NOT minimize the impact of the preamp on the ultimate sound of your system. FWIW.