Great looking TT. I too enjoy Singlepowers amp and headphones. Though I understand what your friends are saying about fidelity of sound being expensive to equal in speakers...you are missing the presentation that only speakers can bring...there is still something about speakers even if they do not resolve as much as headphones. This is just a counter to what your friends are saying by someone who enjoys both very much.
It appears that you have some machining background!?! I am debating a similar idea to build my own TT. Thinking down the air bearing route...we'll see...