@Bobster50 - What you require really depends many things...
How much effort do you want to put into getting "superb sound"?
- for a very good sounding digital "front end" that streams and comes with an on-board DAC and pretty good analogue stage you could start with a Bluesound Node 2.
This single unit comes with an interface App available on iPhone/Tablet, Android Phone/tablet, Windows and Mac platforms.
I burn the music into the following library hierarchy
- Artist
-- Album
---Tracks
I use DB Poweramp and convert all CD files to AIFF format
I have everything from Mp3 to 24/192
To improve the sound you could look at other streaming devices from companies such as NAIM - but there are lots out there that provide these features
You could also add a better external DAC to the Node 2 and given that you are getting a tube amp I would take a look at the Lampizator lineup. But you could also save that for an upgrade much later
The above is a very easy approach to digital music of very high quality.
The Node 2 can attach to a LAN using Wireless or Ethernet - which is far better than USB (i.e. for the laymen). I have a NAS drive that stores all my music and the Node 2 links directly to it
You can also get the Vault 2, which has a hard drive on board - I understand importing your iTunes library is pretty easy.
Another option - You can use a computer to stream, but then there are the constant software upgrades which often result in incompatibilities between the various software packages - it can get messy.
By comparison, the Bluesound software upgrades are simple to install and they work.
I started out by using my computer feeding a v-link192 USB/SPDIF converter into a Schiit Brifrost DAC. My wife would not go near that setup.
The Node 2 -
- Sounded better
- was much easier to setup
- was compatible with all my Android devicess
- compatible with my iTunes Library
- easier to operate
- has manual controls on the top of each unit for Pause, Volume and Next Track
I also now have the Power Node 2 for my AV system and a Pulse Mini for outdoor music
The Node 2 should get you and running fairly quickly and their technical support is very good
Once you get your feet wet you can venture into higher end products if desired, but the Node 2 provides extremely good quality sound
Regards - Steve