Well folks, I am back! Been promising a thorough review of the iDSD Pro versus the RME AD1-2 fs (4990 chip model).
I started having major heart problems just a few weeks into my process of reviewing. Got better, had a few setbacks unfortunately, but have been healthy enough the last few days to complete my RME 'brain acclimation', and made tons of quality notes on the way, assuming I can read my left handed chicken scratches. Doctor's handwriting looks like master penmanship compared to mine! I now have the iDSD back in for direct comparison to my notes from the RME. Full review will be done soon, assuming I stay well, but I will post this tidbit over here on the iFi side of things (I have a post or two about same shootout over in the RME thread as well, but they aren't likely ready to hear this yet

)
Look, the RME sounds amazing, and I know a lot of folks love the synergy it has with the iFi Pro iCan. That actually makes a lot of sense based on what I am hearing. The iFi 'sound' could be very complimentary to what RME has going on. But I can't speak on that from any experience whatsoever. I would call it an 'semi-educated' hunch.
Here is what I CAN tell you right now, unequivocally. The iFi iDSD Pro used as a DAC via line outs is just playing in a higher league sonically. It really is. After a couple months of keeping the RME in the system, changing nothing, not the headphones, no tube rolling in my Icon Audio headphone amp, nada... just switching over to the iFi produced a dramatic effect. It really surprised me it was as great as it was. I was expecting some long in-depth detailed listening to make a decision simply on sonics as a standalone DAC, not considering any other features, bells and whistles, etc.
The iDSD Pro is more refined. Treble has more 'air' and sparkle' while never sounding strident or harsh or sibilant. Soundstage was notably bigger and more enveloping than 'flat'. The RME strength is wonderful midrange with a non-fatiguing treble and powerful punchy bass. The iDSD midrange, however, just has an element of tone, sparkle and realism to it. It is truly beautiful. You forget you are listening to a box processing numbers and just get lost in the music. Yes, the iFi plays beautiful music. And not in some inaccurate euphonic way. It sounds natural in every respect. Voices male and female have resonance and richness that sound like they are right there with you, not being played back via a file. Strings... oh my. If you are a classical music listener, (I kinda have to be since my college studies were in classical piano) strings are reproduced with a richness and a capturing of overtones that I just don't usually expect to hear from digital equipment. Bach Cello suites were almost a religious experience on the iDSD.
So the iDSD Pro is NOT one of those DAC's just put on for the background music whilst you work away at something else. It has a musical beauty that GRABS you and demands to be heard.
Once again, I say measurements, shmeasurements. I have seen the Stereophile AP results along with commentary. Also seen Paul Miller's AP measurements that would seem to be more in line with what I would expect from Thorsten and his engineering team. These DAC's are now operating at such miniscule levels of distortion and noise, even the smallest differences in setups can create drastic swings in results. I admit to being a closet measurement guy who always goes to his favorite pet FFT's etc. (those would be filter impulse transient response and ringing, filter cutoff, order and slope and image rejection, and the J-test.) I have also seem measurements of the RME DAC that would seem comparable to top end stuff; and yeah it does sound great. BUT....
YOU STILL HAVE TO USE YOUR EARS!
And a proper review needs the weeks and months for your brain to absorb and adapt to the sound signature of the DAC. Lot of folks mistake this for break-in...well, yes and no... it's more like your brain that is being broken in. (let me stop here and tell some of you to go ahead and put your weapons down. I DO consider electronic break-in a real phenomenon. Especially things with moving parts like speakers and headphones. To a lesser extent things like caps, resistors etc, but any effect you are likely to hear is very subtle and starts to merge into the time frame of aforementioned 'brain' break-in.)
But again back to actually listening to a device rather than reliance on magazine reviews and posted measurements. This Dac comparison is all the proof I need that the proof is in the listening.
And yes, the iFi iDSD PRO as a standalone DAC thoroughly outclasses the RME in just about every aspect. The RME does get points for tight, deep clean bass response, and EARLY on in the process, I was hearing faster transient response from the RME. But that all gets re-evaluated now as I start the officially review the iDSD Pro and compare what I am hearing to the notes I made over the entire review period for the RME.
But, even now as I start the meticulous evaluating and notating the iDSD Pro for my upcoming review, it is already so obvious the price difference in the two DAC's is merited. If anyone thinks the iFi iDSD Pro is sacrificing sound quality for 'bells and whistles' that is a mistake. It sounds like what one would expect for a standalone DAC around 2.5k, and that is before you even get to the part where there is still as yet a very good headphone amp built in as well. And that feat is pretty damn impressive to me. Actually, strictly on sound quality, I am going to guess it would take quite a leap in investment to find something notably better sounding.
Oh and one final teaser note.. MQA. I am not interested in all these arguments pro and con about the format. All I know is when I heard it for the first time on the RME with ROON acting as core decoder and 'unfolding' to a high rez file the RME could play, it blew me away. I have never heard one of my fav albums "Morph the Cat" sound that good. And now with the iDSD Pro back in, I am hearing the full MQA experience as the iDSD Pro FPGA allows it be the only full MQA decode and render in iFi's lineup. If I am wrong about that, just let me know. MQA. Through all the controversy, once again, my ears are deciding for me. The best sounding playback of "Morph the Cat" is now even more so the best I have ever heard it. WOW.
Okay, that was a lot for just a quick teaser. I have lots of music to re-listen to now via the iDSD Pro, then take the time to sum the comparo up and put a bow on it. Gosh this is a helluva lot of fun... GREAT distraction from learning you have a congenital heart defect in your early 40's

So back to enjoying the music! Make the best of your time on this blue sphere. Be kind to others, slow down a bit, enjoy the ride an all the blessings you have even RIGHT NOW. Tomorrow is no guarantee!
PEACE!
And thanks iFi for what is the the best DAC I have ever had in my system, period.