Thank you for all of the info!

Thanks! Just curious: have you used the D1 as a DAC/preamp with a power amp (for speakers)? That's what I'm really gunning for, at this point (as opposed to focusing on the headphone amp experience). It's my Cambridge SX-50's that need the most love, as opposed to my Sennheisers 

Thanks for the heads-up on the ODAC!   Does anyone have any experience with Maverick Audio? I'm curious about their TubeMagic A1 amp coupled with their TubeMagic D1 DAC. The A1 doesn't look like a power horse, but it's a tube/solid state hybrid that could offer the sound I'm more interested...

Thanks for the suggestions, so far — I'll look into them. Just for the sake of clarification: the FiiO E9 still works just fine. So, I still currently have a headphone amp (it's not amazing, but I enjoy it just fine). Also, the living room is the size of a larger bedroom — it's not too big.  ...

I've been reading these forums for audio advice for years now — finally decided to post a question for my specific situation.   My audio setup was my iMac running into a FiiO E7/E9 DAC/headphone amp combo (via USB), and running the line out on the E9 into a Harman Kardon HK3480 2-channel amp...