Which amp, specifically? They do it on ST100, M180, Apollo, and even old Zeus.
I went from stock 2010 Apollos to 2017 Apollo Dark. To be quite honest, I feel the stock Apollo were a better value. If I could have this back, I would have stuck with the old Apollos. But everyone is different, and you will find others gushing about what the upgrade did for them.
Two caveats to my circumstances:
- I had already rolled excellent NOS small tubes into my old Apollos. Which negates the biggest sonic upgrade from the "Dark" model (which usually comes with RCA clear tops and Telefunken smoot plates - there are better vintage tubes than this).
- I don’t think I like the premium Mundorf EVO coupling caps that go into the Dark models (standard models use plain white M-Caps). I wish Rogue offered a couple choices of premium caps.
The best upgrade would be to move up to the next bigger amp model, culminating in the Apollo monos. It does make a difference over the M180, even if you don't need the power (I have 96dB Tannoys). Unfortunately, I think they only offer the Apollo in "Dark" form now. But Apollo and Zeus amps are a GREAT deal used, if you can deal with shipping / transport issues.