Ah, but that’s just it. You said you wanted a “lossless” capture method. You have to make a new recording that will capture the audio and put it on a new file, there’s no getting around that. As for the format and channels, while there are devices that capture audio in 5.1 they are all lossy. I know this because I myself have searched high and low for such a device that captures 5.1 sound in LPCM lossless format and it just doesn’t exist in the present time. If you want lossless, you’ll have to stick with 2.0 sound. If you’re willing to chance it on AC3 codecs and you’re not concerned with capturing in 4K, you might want to invest in a Hauppauge, those aren’t bad for $150.
When I said lossless, I meant pull the audio as it is being sent through by the broadcaster. However, I see what you are saying. The downside with Hauppauge (for the most part) is that if I stay with the cable provider, they still broadcast in MPEG2. I believe all Hauppauge devices capture in MPEG4 and only up to something like 13.5 MBps.
Thanks for your help!