Next step up from NAD- PP2

I'd say the phono stage is your weak link. Everything else looks super. What isn't the phono stage accomplishing?

My Lehmann Black Cube SE, bought here used, was a very big step up from my receiver's phono stage chip, but not a night and day difference - more a difference in subtle details.

In my experience, entry-level units like NAD, Parasound and Musical Fidelity sound painfully two dimensional and lifeless when compared to moderately-priced tube-based phono stages. In particular, I'm thinking about a $600 Wright WPP100C and a $650 EAR 834P, but these may be beyond your budget. All things considered, a good phono preamp can make a huge difference. Don't underestimate its importance.

A Jolida JD-9a would be a nice upgrade for $350 as Viridian suggests.

If you're handy with a soldering iron, and willing to build a kit, you can get top-notch performance on a shoe-string budget.

I was going to recommend the Bottlehead Seduction for $279, but it doesn't have enough gain for your cartridge.

The Juicy Music Tercel kit would be an excellent choice for $395.

Jim Hagerman's Cornet2 kit is a giant killer for about $400-500. The instructions are easy to follow and Jim is extremely helpful. There's an active DIY group at Audio Circle and Audio Asylum if you need advice.

I encourage you to check out this forum:
please help me choose a new budget phono pre