Streaming For Beginners

+1 for Bluesound Node 2i as a great place to start with the idea of stepping up to a better outboard DAC down the road if you really get into it.  But to really take advantage of it, I suggest subscribing to a good lossless streaming service like Qobuz or Tidal which stream at CD or better quality.  Node 2i retails for $550 but can be had for less.  New, used, or refurbished Node 2 or Node N100, earlier models in the Bluesound lineup which all utilize the same user friendly Blu OS user interface software would also be good places to get a start.

Lots of possibilities, depending on your system. A list of what you now have would get you relevant advice.

Lexicon DC-2 Digital Controller 
Sherwood A/V Tuner Preamp 
3 channel amp
2 channel amp
DVD player
DVD recorder 
Reel to reel player 
Cassette player
5.1 sound

I forgot turntable and
Subwoofer 

Does the Sherwood have USB input?