I am making my way towards the uber-transparent HD800 and Beta 22 combo. I just ordered the HD800s yesterday and am in the planning stages of the Beta 22. (I have a Crack with Speedball until it's finished) Currently the plan is for a 5-board Beta 22 for balanced or actively grounded single-ended listening. Since this is a few steps above building the Crack, I thought I'd ask some questions for anyone who has built a Beta 22 or is knowledgeable about DIY amps. 1. I am unfamiliar with the process of setting up the chassis. I have been looking through the catalogs of the recommended manufacturers (Par Metal appears to be out of commission for now). The logistics of finding a box capable of fitting two Epsilon 22 boards aside, it looks like you're supposed to order the case without any screw holes or other openings for the external parts to come through. Could someone explain the best process for getting the case machined? Are you supposed to be able to do that yourself as well? 2. Does actively grounding the single-ended channel make a perceptible difference? 3. If yes, I'm thinking 5-board instead of 6-board since I don't anticipate any tandem listening sessions. Nonetheless, is there any reason I couldn't wire both single-ended channels to share a single active ground board? What effect would this have? 4. If anyone has a suggestion for a good, highly transparent balanced DAC to eventually go with this setup, state it. Price is not an issue as long as you tell me why it's worth it.