Upgrade Advice: Moving from Rega IO to Fosi V3 Monos + ZD3 (Preparing for KEF LS50 Meta)

[fjaviys]

Hi everyone, here a new at ASR as a user, but not as a reader.

I am looking for objective advice on a planned upgrade path for my desktop HiFi system.

Current Setup:

• Room: Small office (12m² / ~130 sq ft).
• Amp: Rega IO (30W @ 8Ω).
• Speakers: Martin Lab 38 (Sealed monitors, similar to vintage acoustic suspension).
• Sources:
  
  • Digital: Squeezelite endpoint (RPi) + SMSL SU1.
  • Analog: Rega Planar 2 turntable + Nagaoka JT-80 cartridge.

The Goal: I enjoy the "warm/rhythmic" sound of the Rega IO, but I am planning to upgrade my speakers in the near future to something harder to drive, likely the KEF LS50 Meta or B&W CDM1 NT. I feel the 30W of the Rega IO will be the bottleneck for these low-sensitivity speakers.

The Proposed Upgrade: I have already ordered the Fosi Audio ZD3 DAC. My plan is to replace the Rega IO with two Fosi Audio V3 Mono blocks (48V/10A PSU) to ensure I have enough headroom and current for the future speakers.

The Dilemma: Connectivity & Preamp: Since I need to integrate both a Digital Source (via ZD3) and an Analog Source (Turntable) into the V3 Monos without a full-sized integrated amp, I am debating between two connection schemes. I would appreciate your technical input on which is better:

Option A: The "Purist" XLR Approach (Input Switching)

• Digital: Streamer -> USB -> Fosi ZD3 -> XLR -> V3 Monos (XLR Input).
• Analog: Turntable -> External Phono Preamp -> RCA -> V3 Monos (RCA Input).
• Workflow: I would use the toggle switch on the front of the V3 Monos to select between RCA/XLR inputs.
• Pros: Maintains the balanced chain for the DAC.
• Cons: Ergonomics (switching two amps manually).

Option B: The Centralized RCA Approach (Switch Box)

• Chain: Fosi ZD3 (RCA Out) + Phono Preamp (RCA Out) -> Passive Switch (e.g., Schiit SYS) -> RCA -> V3 Monos.
• Workflow: Centralized volume/source control via the Switch.
• Pros: Convenience.
• Cons: Losing the balanced connection from the DAC.

Questions for the community:

1. Is the benefit of the XLR connection from the ZD3 to the V3 Monos audible/measurable enough to justify the inconvenience of Option A? Or is Option B transparent enough for a short run in a small room?
2. Considering I come from a Rega IO, is there a specific Phono Preamp recommendation that pairs well with this Class D setup to maintain some "analog warmth"?
3. For those using Fosi V3 Monos with KEF LS50 Meta: Is the power/current delivery sufficient to open up the bass on these speakers compared to a traditional Class AB amp like the Rega?
4. Any other options or suggestions for my upgrade?

Thanks in advance for your help!