Thinking Hybrid Integrated.

+ for Modwright.  No experience with Dan’s amps but he tube modded my OPPO Sonica DAC years ago. Does great work.  Stand up guy. 

@cantorgale thanks for the information regarding the Heritage MK2 upgrade. I have one on order now and am getting excited.

As for the stock tubes, have you done anything or know of anyone using different tubes in the Heritage?

I just bought a BAT VK3500 from MusicDirect. I scored an open box, but they are on sale for $9K if you are in the USA.

Very happy - if you have any interest check my virtual system - I'm moving from all tube, details are there - not updated with the BAT yet as I have 60 days to return it but I doubt that will happen. 

Heaven 11 Billie mk2

https://holthill.com/products/heaven11-audio-billie-hybrid-amp

@ja_kub_sz 

Sorry. Thought I’d answered your Heritage tube question before.  Replaced the Tung-sol EXC803S with NOS MULLARD mc1.  $$ and hard to find. More stability to the sound. More solid bass.