Well, the Brooklyn has a switching power supply. The Manhattan has two separate fully linear power supplies with a massive amount of power supply capacitance. Just this fact alone would tell me the Manhattan is a significantly superior DAC. That being said, I'm not sure that it's worth $6k for this DAC since the DAC still uses op amp modules for its analog stages. I suppose if you absolutely wanted to get full hi-res audio from Tidal, you will need an MQA DAC. However, there are many other DACs on the market that I think would be better than the Manhattan and much cheaper that use discrete analog stages (and in some cases Class A analog stages). Examples:
L.K.S. MH-DA004 ($1600)
Krell Vanguard DAC (you can pick these up new-in-box for 40% off at $2700 now).
Denafrips various models (somewhere between $2k and $6k).
etc.
You can still play Tidal through a non-MQA DAC, but you're limited to 44.1kz or 48khz sampling. In my opinion, if it was a decision between 96hz MQA or 48khz through a superior DAC, I would take superior DAC every single time. MQA is a encoded wrapper that just contains the original 24/96 FLAC file data and enforces a restriction on sampling rate if it's not played through an MQA DAC. To me, this is a marketing ploy to force you to buy a MQA DAC. As a result, the MQA DACs can demand more money than they are actually worth.
I suppose MQA also serves as some sort of "copy protection" for Tidal when they stream down hi-res audio, as there are similar restrictions through HDMI/SACD type audio.