Setup addition advice - DSP or Graphic EQ?

Hi friends!

I recently posted my budget system: My Current Setup. I've since added a Wiim Mini streamer. Quick system summary so you don't need to click the link to the other post:

Record deck : Dual CS 505-3 with an Ortofon OM10 cartridge/stylus

Ampliier : Marantz FM-66SE

CD deck : Philips CD610ii

Streamer: Wiim Mini

Speakers : Wharfedale Mach 5

Currently everything runs through the Marantz and out into the speakers. The sound is high grade but a bit thin - it's a combination of my room, and the speakers liking a bit of power before the really engage the lower frequencies.

The Wiim Mini has a room correction feature, so I used that and as expected it decided the lower end needed some boosting and I can't believe the difference it made - the addition made everything come alive in the room. The issue here though is that it does nothing for the vinyl and CD sources.

So - I need to add EQ or room correction. The Marantz has a tapeloop so I can feasibly add something there that would apply to all sources. What I'm stuck on is whether to slot in a simple graphic EQ and tweak myself, or something like a Mini DSP 2x4 and use digital tuning and room correction.

I think I also need to add a DAC between the Wiim and the amp as it's a little muddy on its own DAC- if I do this, would it have a bearing on the EQ/DSP question too?

Any advice is greatly appreciated here as I'm now way over my head in trying to figure this out!