Responses from moemoney

Best IEMs ?
I Love my Custom HJ Laylas 
Best high-end headphones with noice cancellation ...
If you are using iPhone then Apple’s new headphone Air pod Max would be a good choice I never hear them but do have there AirPod Pro. And to my ears the noise cancellation is about the best that’s out there and nothing tops there transparency mode... 
Closed back headphones and Focal
I have to 2nd the Sony MDR-Z1R great closed back and a fun sound. 
M scaler or Cables
I have the Hugo 2 / Hugo 2 go using the Empys as my bedroom system with Tidal playing within Roon. it sounds great to my ears. I can only imagine how the TT2 would sound.   
Woo AW22 1st Gen or 2nd Gen - Do they sound the same? Same build quality?
I have the wa 22 2nd generation I never heard the first generation so I can’t comment on that all I can say is with the second generation the amp is also a preamp that’s why you got the XLR outputs from what I’ve read the first generation is a lit... 
Bluetooth Buds?
I have the sony wf-1000xm3 and love them. 
Meze EMPYREAN + Benchmark DAC3B + Benchmark HPA4
I also have the Empy but only have around 20-25 hours on them so far I’m not feeling them for some reason, maybe they need more break-in. Anyway I order the lavricables grand silver cables and will continue to break-in them in. I also have the Son... 
Headphone amp + DAC + Volume + ROON READY
I Just pick up a Chord Hugo 2 + Hugo 2go for my bedroom. I got it because it's a one unit solution and it's Roon ready.   
New DAC not streaming hi res files
I not 100% but I'm don't think coax goes up that high, you may have to try USB 
Can a 75 ohm digital rca cable be used in place of a regular rca interconnect?
There was a time when I use to use a Nordost RCA Valhalla cable as a digital cable and it seem to work fine at the time. At least until I was able to save up for a real digital cable.  
What's the deal?
I wish Audiogon would do something about it, it's gotten out of hand. 
MAC to DAC connectivity
Well whatever you do, you can not run USB cable longer than 10 feet   
I have the BDP-1 as well and just purchase the Ayre Codex about 3 weeks ago to replace my BDA-1 and it's  definitely an improvement all around more detailed, soundstages  more open and imaging is more pin point. Also works very well with my new Fo... 
Cary SLP-05 pre + Krell 302e/402e sound? Should I consider a different power amp?
 I don't believe Krell recommends using tube pre amps with there amps.  
Best Vintage Dac??
But to answer your question I  might look towards a Musical Fidelity Tri-Vista DAC