Yep redwood burl here
they came out super nice! Can't wait to see your Elm Burl finish. Also this is a potato picture, DSLR will come out for the review photos.
First off the fit is impeccable, I have not have vented CIEM's but I have to break the seal of my FIBAE and P350's occasionally to alleviate pressure, none of that needed here.
Sound wise I need more time. typical warm, full lows with excellent impact and control as you would expect from 64 Audio, but the highs are much better compared to the old U6. The sound is much more open and airy and this is with M20 modules. The U6 is much darker, with more focus on sub-bass and sweetness, but missing out on treble detail and air. The A6t is not a reference tuning as such, but it is well balanced and super easy to listen to, yet still packed full of detail. I think the M15 modules that I have may make it more reference like by toning down the bass impact a little.
I'm a big metalcore fan, and these handle that genre really well. Perfect amount of impact and sub-bass for breakdowns, but with the separation and clarity to pick apart the complex mixes.
Edit: I have just popped in the M15 modules, and I think these are the sweet spot for me personally. Still plenty of low end impact and the sub-bass rumble is there, but it is a little less prominent which allows male vocals to shine through a bit better. The highs are a little more pronounced, but they are not hot or fatiguing to my ears, they still retain a smooth nature.