Streamer only

You can isolate your DAC from your computer quite easily.  The majority of the the noise generated by the computer is in  the power line that runs side by side with the data lines inside the cable.

A simple $5 USB adapter that removes the power from the cable and a powered USB hub does the trick for me.  With the proper  playback software my USB PC sounds better than the PI2AES using AES / EBU, I2s or coax.

@soix 

I have a Node 130 and use the USB output to my DAC; two other posts mention the same thing.  You repeatedly have said the Node lacks the USB output, which only applied to older versions of the Node.

@pal 

I recently added a Teddy Pardo linear power supply to my Node, and it fleshed out the tone of instruments, added more power to the bass and reduced the slightly grainy textures of some content.  The Node by itself was quite listenable, though.  I would concur with others that a used Node 130 with an external power supply would be a great way to get a streamer within your budget that would perform above its cost. 

I haven't used other streamers, so I have no direct experience with other streamers' user interfaces, but I concur with others that the BluOS is quite good and is operated from an iPhone app.  Also, the Node is really designed for wi-fi streaming and allows you to see the strength of the wi-fi signal it receives, which is very useful since a strong signal is needed for optimal streaming of hi-res files.  Last night it showed me an unusually weak signal, so it took just a minute to reboot the Node by one touch of my iPhone, and that greatly increased the signal strength.  This occurs rarely, and only one reboot is generally needed.

The BluOS is supposed to allow you to add audio files from a hard drive to your BluOS library so you can use the BluOS to control listening to those files.  This is one area where the BluOS has not worked well for me.  It took hours with customer support to get that to work, and then it didn't last long. 

To the OP, you have a very good system. But it sounds like streaming is a "new fangled" idea to you. Perhaps you have a nice vinyl set up or play a lot of CDs. 

Given that streaming will likely "take hold" and you will love it and its convenience, I'd suggest getting at least a Bluesound Node (the ones with USB out if you need that).  Nothing wrong with the WiiM products for their prices - I have a couple of them in various rooms and one in my garage. They work excellently and their software puts that provided with some $4000 streamers to shame. 

The Node can always be sold or repurposed or given to an interested relative later on when you decide to get "something" better. Or you might be perfectly happy with the Node feeding your integrated and call it a day. 

You didn't mention if you have ethernet near your stereo or will have to use Wi-Fi. If Wi-Fi, beware the iFi Zen. Unless iFi has done anything to fix it in the last year or so, it has a lot of bad online reviews for its frustrating connectivity that drops often.

Ironically the extremely cheap ($99) WiiM Mini in my garage NEVER drops its signal.  

Have fun! You'll be discovering a lot of new music to enjoy. 

One thing people seem to ignore (correct me please if I am wrong) is that to use the "better" clock in your external DAC over the one in a "cheap" streamer, you must use asynchronous USB or I2S, otherwise the clock in the streamer is doing the "driving". The use of Toslink optical or coax outputs from a streamer limits you to however good the clock in the streamer is. At least this is what Hans Beekhuyzen implied in a recent YouTube video of his.

The thing is, there aren’t many "cheap" streamers that have USB out other than those particular models of the Node that I’m aware of. (Not counting any home brewed, noisy, Raspberry Pi streamers). Figure that the clock in the Node X or his integrated is better than one in any of the WiiMs.

Roon Nucleus for $750 on HIFI shark.