Hello everybody ,
I want to post some impressions about the Apollo. I am folk singer/writer, one man band. My sound was my main concern starting with the microphone and ending up with the converters. I have always been a Motu fan. They were not the best in terms of conversion or preamps but definitely they where musically very close to what I want and very very stable with an outstanding customer service.
For last 2 years or so I made some money out of music (yea I know I was surprised too) and I wanted to upgrade my audio interface. I bought the following: Lyra Prism One, Antelope Pure 2 and Apollo 8 Quad blackface.
These are my impressions:

Lyra Prism – outstanding sound in-out, dead quiet but also with a very unintuitive mix software, a real pain to use. To me the sound was top notch, but not to my taste. I can not describe, it was just ..boring. Of course you can color with outboard gear and that is fine. One thing worth mentioning is that as expensive as it was the main volume knob was cheap plastic and the front LEDs were just some lights for indication of music, nothing that you can rely on.

Pure 2 – most beautiful converter/audio interface. I liked the sound of this one the most. They have done something to this unit. You can overload the converters and have a very pleasant recording almost like a tube saturation. Very nice interface software, beautiful design, all around. The bad ? There are little annoying things that makes you think about the price you paid like: change the recording frequency you would have to restart the unit. I had different sessions a different with different recorded freq and so the unit would just freeze. Main volume know had a click sound that I didn’t like, latency issues, especially if you run VI. That was a big one for me. And then from time to time the unit was not shutting down properly, just staying in some limbo mode. Other times the USB port would not recognize the unit. Antelope knowledge base is non existent, and so you have came here to ask questions. The online help chat is not that useful. True in fact is you that you can write to the support team and then in the next 24 to 48 h you can get a response. I was not ready for this. Motu does a better job.

Apollo- beautiful hardware and software, quite heavy and big, good connectivity, nice materials on the main knobs, easy to work with. They say the unit is transparent I would say it is on the warm side. It is not that quiet especially on the headphones output, this is in respect with Pure 2 and Prism, otherwise I would not consider this as an issue. Outstanding integration with the UA plugins. The 610 unison is probably the best emulated plugin. I could not tell the difference between the hardware and the software one. The Neve and Api unison plugins in my opinion are not good impersonations of the real thing. They do sound good but there are not close to their real counterparts. Same goes for the Manley Variable Mu. I had this unit for good amount of time and I believe that the plugin is way off. However the plugin itself adds a very nice warm character to the mix or track. I would recommend this plugin to everyone. It glues everything together without effort. Just like the Manlu Mu you just cant make this plugin to sound bad… maybe this is where the two resemble.
Sound wise Apollo ? love it. Compared to the Pure 2 and Prism is just a different flavor of the same good sound quality.
I kept the Apollo because of the work flow, connectivity and plugin integration. In my opinion at this level the sound is trivial. Any unit in this price range will sound just as good. However I still believe that Pure 2 had the most pleasing flavor sound wise.
At the end of the day I think customer support, work flow and high quality add-ons, will push you towards the product. All other technical aspects are mature enough. As of now with Apollo you get probably the best plug-ins on the market, additional hardware (satellite quad ) and the same good sound as all other big guys on the market. I have seen now that Apogee is offering Waves plugin bundles along with their product line.
This is my personal experience and it should not be seen as “the rule to follow”. For you it might work in a different way. I posted because maybe others are going through the same decision struggle as myself.

take care everybody