Is upgrading pre worth it?

Fortunately, the Creek OBH-22 seems to match most of my equipment pretty well - so, it is a bargain for me - though, I’ve not tried it with all of my various speakers, amps and sources.

Not an EE but, I agree - Impedence, gain and current matching is a critical factor in attaining the best sound from your components. I became aware of impedence and gain matching, with some headphone amps I have / had.

I wondered why the X-CAN v3 would sound great with my high impedence phones and less so, with my low impedence phones, while the X-CAN v8 just the opposite. It turned out to be an impedence matching issue. Makes all the difference.

Truly cheap passive, Schiit SYS, $50 + shipping.  I bought one just to play with. Use it with my Dynaco ST-70 amp. 

I got rid of the denon. I got the Rogue pre 99 super magnum. It sounds pretty good. I also bought the Antelope zodiac DAC pre. A hand full of people not knowing what’s what for gear, but with a pretty legit music background thought the Zodiac alone as a pre/dac sounded better than the Rogue pre with the Zodiac working together. This is with cheap speakers. I have Penaudios coming in next week. That will be the real test.. So yea ROGUE ST100 needed a pre, who knew.. The difference is real. 1500 real? Yes I would say so and I like to have my money in my account.

Excellent!  Enjoy listening!