* As a stand alone dac -- it has digital and analogue outputs, it has no digital input other than its network signal. I guess that is what you mean, but I wasn't sure.
* Quality of internet radio channels --- probably the root of everything, and I guess it depends on the station. I enjoy my BBC, and I have have had a couple of very pleasant sessions with Internet Archive music.
* Bufferring issues --- very occasionally
* Sb used with external DAC --- Don't know, would like to test!
* Can we type, search by the name of the artist ex: peter white (smooth jazz)/ (Classic Rock) Allman brothers? --- Not sure! I always work on the mental model of directory listing, rather than music library, so I do not look for those functions. You can download the PC software and try it: you can even get an add-in to make it play on your PC rather than over the net. You wouldn't want to do much text entry on the remote, using the wheel; tedious.
* Can we see the album art cover on the remote screen --- Yes I think so. I don't have the source art to display!
* Is there a volume control on remote and does it increase the gain/loudness --- Yes
* Warranty --- I don't remember
* Adaptor -Voltages issues bought mine in UK: it came with a couple of plug adapters, one for UK, the other maybe European, don't recall. Input voltage: 100-240
* Performance- resetting/ hanging issues --- I have had some problems. It strikes me as being a bit of a geekish device! The remote is actually a linux computer that you can log into and tamper wit h (you can also do a factory reset, so no worries). The one thing I have never made it do is act as a stand-alone internet radio device (with no loacl PC running server software) --- but I think many, many people do: it must be just me! The remote is not very snappy; I prefer to control the device from the PC --- which is a pity as the remote is actually the most expensive of the two components!
You can use the remote as an independent player, though, with earphones, though it might take a bit of geekery to do it. The capability is there, but not officially supported, it seems. I did make it work. I think the is also a capability to control other devices via infra-red.
I don't use mine very often, else I'd be able to reply more fully. I often regret that, when my hifi and pc were near by, the connection was achieved over wires at a fraction of the price!
You can download the manual from the Slim Devices site. I always think manuals are much better buyers' guide than sales literature!
Slimdevices runs a forum that you might find interesting, and will probably find useful if you buy: -->
here.