If you need a solid DAC for converting an opaictl digital audio signal to RCA or RCA to opaictl, this is a nice unit at a good price.I did some research into DAC chips. This unit contains a very good DAC chip. Having said that, I ran the audio signal from different devices through my Sony HDTV (2010 basic model) via an HDMI cable. The Sony HDTV has a DAC in it too and RCA outs (analog out is increasingly rare on HDTVs). I was able to compare audio quality running the audio through the HDMI via the HDTV DAC to RCA and then to an amp AND from different devices directly with opaictl (Toslink) to this DAC, and then RCA to the amp. The speakers were Magnepan MMGs. All digital audio signals that had Dolby Digital were reduced to two channel stereo in various device settings or were that way to begin with. (If your device cannot change to two channel, all you hear is noise. Some HDTVs with only opaictl out might not be able to turn Dolby Digital off.For Blueray/DVD, Pandora (via Roku XR opaictl out), iTunes music I bought directly from Amazon as MPEGS, and Netflix, I could not discern any difference from the FiiO D3 DAC compared to audio processed through my Sony HDTV (DAC in it unknown). I think this is in part less to do with the DAC but simply that these devices and recordings are not technically complex enough to push even a basic DAC like this. What you put in is what will come out, in this case. BTW: the Roku DAC is quite good too IMHO. Better than the Sony built in DAC. On the XR, it has RCA out on the back. I use that direct to the amp for all Roku audio.However, when I played audio CDs (Jane Monheit, Never Never Land) I converted to Apple Lossless in iTunes sent over WiFi to an Apple TV 2 to this DAC to my amp, the audio was better. I could also hear the tape hiss on older digital conversions of classic jazz albums I own on CD (Oscar Peterson, Night Train). I would assume, in this case, hearing hiss is a good thing as it shows you that the DAC is capturing the full recording.I also owned an MCM 24Bit/96K D/A converter which uses the Burr-Brown DAC. The MCM is supposed to be the best low cost DACs out there. But, frankly, unless you are an audiophile, save your money. This FiiO DAC is fine especially for the PRICE.All testing was done with direct amplification. No equalization or base/treble modification.Clarification: It was not ACC it was Apple Lossless I used! My mistake Hopefully the audiophiles who freaked out will now calm down (except for the CD fanatics).