I just finished building a Chime last night, and it sounds as good as I remember from the Chime-across-America tour.
Before I built the Chime, I put the HagDac into a chassis with RCA's, and switches for the digital filter and phase. It sounded really good powered by 2x12 volt SLA batteries, using the buffered outputs from the onboard opamp.
Here's an idea for your candybag.
Why not take what you learned building the HagDac, and build a compact rechargeable battery powered (2x9 volts?) portable DAC with a USB, toslink, and maybe SPDIF input. Headroom makes a product that's similar, but the design isn't as good on paper as the HagDac (I've never heard the Headroom product). The HagDac sounds really good with the opamp output and battery powered. I bet it would be the best portable DAC available, and it would be cheaper than the Chime.
There are a lot of headphone geeks out there that are into portable gear and would love to have a fantastic sounding portable DAC. You could include an 1/8 inch line out jack, maybe RCA's too.
What I described might be a little big, but they fit most of that functionality into the Headroom DAC in a small package. Heck, you might even be able to get Headroom to sell it for you, they sell competitors products, even other companies amplifiers. You could even offer it as a kit, there are a lot of guys doing surface mount kits over on Headfi.org now.
You would mostly be combining work you've already done, I bet you could whip up a board in no time. Put it in a hammond case, something like the 1455 series, with 2x 9 volts, a battery charging circuit, and a jack for a battery charger, and you've got a great sounding DAC you can use with your computer, a portable device with a digital out, or your home system. Don't know how much you'd end up charging for the whole thing, maybe it would wind up costing too much to be an effective product for you, but I think it might be worth considering.
If it was easier to get to the HagDac inside the Chime, it could even be set up so that you could plug the HagDac into what ever you were using, the Chime at home, or the portable case when you're on the road.
Just something to think about.
-Aaron.[/code]