I think the Monoprice is probably a very good unit and a good value (gotta love Monoprice!). The SDA-2 uses a more advanced AKM chip and they’ve paid a lot of attention to improving the USB input, clock, jitter, etc. whereas I don’t see anything about this implementation on the Monolith, which is a little frustrating as this is fairly important. Just going by what I’ve read, your DT1990s are already on the transparent/detailed side of the sonic spectrum as is the Monolith, so I’d be a little concerned that the two together may be a little much and possibly become fatiguing over time. The SDA-2 on the other hand will still give you a lot of detail and transparency with perhaps a little more flesh on the bone in terms of tonality and heft and maybe a little smoother and more refined sounding, which is why I thought it might synergize well in your particular situation. I think both units are great and excellent values, but as with everything in audio it ultimately comes down to personal preference and system synergy so let that be your final guide. In searching around I did find a review from headphones.com that actually compares the two and this is what he had to say. I have no idea about this guy so can’t vouch for the validity of his impressions, so FWIW...
Well, I think these two are approaching AIO from different perspectives. The THX feels wider and cleaner. Separation feels slightly better. More fatiguing treble, and overall not as enjoyable as the Singxer. It feels more “harsh” to me. That being said the THX-788 is still my recommendation for AIO or even DAC/amp under $600, and honestly even higher depending on your preference. The THX-788 is a more analytical sound and it has EQ options (a little hard to figure out at first but once you do it is pretty easy to get around the menu). If you are looking for the best bang for your buck, I would go with the THX-788. If you want a more relaxing involving sound and don’t mind not having EQ options baked in and don’t mind the price, or will be potentially pairing with better amps down the road, Singxer SDA-2 is the option I would go with.
Again, hope this helps and by all means let us know what you find and decide.
Well, I think these two are approaching AIO from different perspectives. The THX feels wider and cleaner. Separation feels slightly better. More fatiguing treble, and overall not as enjoyable as the Singxer. It feels more “harsh” to me. That being said the THX-788 is still my recommendation for AIO or even DAC/amp under $600, and honestly even higher depending on your preference. The THX-788 is a more analytical sound and it has EQ options (a little hard to figure out at first but once you do it is pretty easy to get around the menu). If you are looking for the best bang for your buck, I would go with the THX-788. If you want a more relaxing involving sound and don’t mind not having EQ options baked in and don’t mind the price, or will be potentially pairing with better amps down the road, Singxer SDA-2 is the option I would go with.
Again, hope this helps and by all means let us know what you find and decide.