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just use your phone
I was waiting for somebody else to realise that this was the answer, since the OP explicitly rejected audiophile quality. If you want a standalone device, a no-name Android tablet with all the local files on a SD card plus Bluetooth connection to the amp would be sufficient for any but the golden-eared.
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I guess Android and USB DAC would be the way to go. Unless you mount it somewhere though it's much more awkward to use.
Or just use your phone.
I use my iPhone to stream via Airplay to an Airport Express (A1392) which has a combined 3.5mm analogue/digital out. Sound quality is perfectly fine via an Arcam amp and Celestion speakers, and it's easy to use.
If not Ipad is it worth considering an android device with SPDIF out which would let you use your choice of DAC?