Better 2-channel music

I would recommend a 2 channel preamp with home theater bypass.

I have a Conrad Johnson ET3se for 2 channel and an Emotiva UMC 1 for home theater.

The 2 channel is awesome.

Just about any quality build high-current 2 channel integrated amp will
handily best virtually any AVR for 2-channel audio performance.
The AVR is a yeoman performer crowded primarily AV unibox with
comparative significant cheap design and cheap parts compromises for 2
channel music performance.

I even had the very top Cambridge AVR (ka-ching!) and even it could not
stand in the shadow of my discrete 2 channel integrated amp and discrete
CDP / DAC system in terms of 2 channel audio performance ..... it was not
even close and the differences are not subtle.

As good as the the AVR can be, you cannot realistically expect it to fully
compete in a 2 channel arena ..... full stop.

Accept it for what it is, what it does well, and just live with and enjoy the
AVR even with compromises for 2 channel audio unless you want to
expand as the prior post highlights ( I did a similar thing .....)

- kept my discrete 2 channel integrated amp with a directpass through from
the AVP below to drive the LF and RF main speakers in a multichannel
mode
- discrete 3 channel power amp to drive the centre channel, RR and LR
speakers
- discrete 2 channel power amp to drive the R and L surrounds
- discrete 7.1 channel AV preamp/processor [NuForce AVP-18] for the
multichannel modes ( movies, BluRay concerts....)
- active subwoofer out from the multichannel AVP immediately above for
movies and multichannel Bluray concert ( a manufactured and artificially
contrived audio format but enjoyable in its arena) added bass slam
- discrete ARCAM Bluray player for multichannel and movies

"06-10-15: Pkelly1504
I would recommend a 2 channel preamp with home theater bypass."

I agree. If you don't have a good preamp, get that first.

Thank you Loomisjohnson, Pkelly1504, Akg_ca, and Zd542. I've got the idea now. Will the Emotiva XSP-1 be a good choice?

I find that the weak point with Emotiva is their remote controls. Keep that one in mind. I'm using the UMC200 with an Oppo 105. I let the Oppo do all of the processing. The only thing the Emotiva does is 7.1 volume control and occasionally radio or other analogue stuff. The sound is great. The one really strong point with the 105 over the 103 is audio. Better processors and dedicated 2 channel out.
You could keep the marantz as your controller. It has a better remote than the emotiva. Upgrading to a 105 should solve the rest of your issues. They do should have a 30 day return policy if the 105 doesn't work out for you.