Had a chance to connect up the O2 with the QA350. Having spent two or three sessions with the QA350, it has proven to be a very useful addition. From this, I can now take my own music and use to demo new equipment. For example, been planning on trying out the V200 with my EM4, and now, with the QA350, I can in someway have a more 'controlled' test setup - rather than using the vendor's setup. Secondly, this unit; whilst compact and light weight, is not really body wearable. Even with a jacket or suit, the size is just too large. With a bag, there is not a problem. But issues arise when you are walking around, with a delicate and shortish headphone lead, not the safest approach.
The volume control on both the QA350 and the O2 needs to be no more than a 10 degree rotation from their 'zero' position before the volume gets too loud. Not a good arrangement. I will have to find someway or padding the output volume down, or reducing the gain. This is why the V200 would be a good option, as there are DIP switches on the back to adjust pre-gain. Mated with their V800; which also has output gain selection, could tailor a solution where the EM4 can be used at sensible volume control positions - of which I deem as around 40%-60% of full rotation.
Currently listening to HD Track's 1812 Overture, downloaded as 176.4/24 converted to WAV via XLD, and then down samples by Sample Manager (using isotope Resampler set at 'High' and MBIT+ dithering) to 44.1/16. Just finished it on the O2, and to me, the sound was a little confined, in my head, and potentially a little flat. Having started with the QA350, I can't tell that much difference from first impressions. On a side note, both the O2 and the QA350 have had relatively little burning in time; probably at most 10 hours each. Whereas my EM4 have now got a very healthy 200 plus hours. The volume control on the QA350 has channel imbalance at low levels, important for me cause the EM4 are very listenable at those levels. Also the optical output light is always on, so there is a constant red dot on the main side panel. When the charger is working, I can detect a high pitched noise. Owning to the warnings about Lithium polymer batteries, I am keeping a close watch on them.
Back to the QA350. I dare to say, that with this very casual session, there isn't a lot between them. I think I could hear a few more details with the O2 then with the QA350; and the cannons were more powerful with the O2. In some way, you could feel the cannons - not the full body sensation, but just around the ears, if that makes sense... Both the sound stage is limited to between the ears. I know the EM4 can project sound around the ears (for me anyway).
Now moving onto the Computer setup. This time, O2 front end, from the Calyx, running Fidelia with the full resolution FLAC file. Immediately, the clarity returns! Soundstage is wider - straight away! The setup in Fidelia - 24 bit MBIT+ dither, device sample rate set tup 96kHz with isotope resampler set at 'High'. At this stage, I am running the volume at 100% on Fidelia and using the O2 to control. Changing Fidelia to point at '9 o'clock', has shifted the O2 to be pointing at '10 o'clock'. Differences in sound? A little loss in clarity, but very minor. With dither turned off, and the Fidelia set to 9, I could hear a difference, or missing music, that was there before, when dither is on. Overall, the presentation on this setup is more musical than through the QA350. Oh yeah, the cannons on this were way more body, substance and 'cannon-like'. Night and day. Through the QA350, they just sounded like pop guns, or cannons in the far distance.
The last test is to play the same 44.1/16 WAV file on the QA350 through Fidelia. Oh yeah, the file size is 524.4 Mb compared with 150.9 Mb. Interesting in that the jump from 176.4/24 to 44.1/16 should be a 6 times reduction in information. So, given FLAC has some compression, the full size 176.4 file should, by rights be 905.5 Mb, therefore, the FLAC file has losslessly reduced this by around 40%. But this comparison with the higher res file is moot - the Calyx is limited at 96kHz.
Firstly, the sound stage, again, much wider. The rendering of the music, is more lively and more musical than the QA350. There is a loss in clarity between the higher res file and the lower res. A little more separation in the music and instruments. It is, 'more focused' in photographic terms. But the difference between the QA350 and Fidelia is quite noticeable. I would vote Fidelia in this instance, based on this one track. Again, the cannons on this war much more powerful with more body and substance.
Finally, the same 44.1/16 WAV track through iTunes. Smaller soundstage - less clarity and detail. Very similar to the QA350. If anything, it sounds a little more confused, or muddy, than with Fidelia. What it does sound like, compared with Fidelia, is that there is a limit to the music, in both sound stage, dynamics and clarity. Fidelia sounds like these restraints have been removed. Turning up the volume does not restore, or give iTunes the same energy as it does on Fidelia. The canons are definitely more like the QA350.
After this track, Adele's 'Daydreamer' came up quickly, and it sounds pretty good on iTunes. The guitar strumming and her vocals, focused and articulate. Moving quickly to Fidelia with up sampling to 96kHz, improvements in the sound; but the extent mot as great as that with the 1812 Overture.
Now, what does this short hour session tell me;
- I can hear differences between the same track (source at 176.4/24) played between 44.1/16 and 96/24.
- Dithering on Fidelia is required when using it as the volume control.
- The headphone amp sections on the O2 and the QA350 is in principle very similar - but sure to be differences that can be told over a longer, more rigorous session.
- There wasn't a huge difference between playing from the SD card and the computer. Perhaps this whole jitter issue, etc, is the storm in a tea-cup?
- The soundstage, clarity and body is much better on my Fidelia setup than the QA350.
- QA350 hasn't been burned in.
- Cannon love on 44.1/16; best Fidelia, then by a long margin iTunes, and close behind that QA350.
- QA350 sounds inferior to the computer. Using different files and sampling is surely more of a difference.
- That my opinions or observations can be repeated. This is not a double blind A/B. This is me on a quite afternoon listening to the same track on 5 different setups. Not switching back and forth between each one. Each one in its entirety and in full, followed by the next. So take the above with a grain of salt. Also, this was done with one track, a classical track. At the end of the day, YMMV, and so will mine, from day to day.