[Miraculous]

Yeah, I'm just getting into this whole head-fi thing in the last few months...but I'm just a young guy so I don't have the funds to go crazy.
I got Klipsch Mode M40 cans on a Boxing Day sale after Christmas and soon after picked up a FiiO E10, just to see if I'd be able to improve anything...it set me off on a very expensive little journey, let me tell you. I got the beyerdynamic DT990 Premium 250 ohm a week ago or so, and they're decent with my E10, but I ordered an O2-ODAC combo from JDS Labs a couple days ago, hopefully they'll drive them with a bit more definition. Also, it keeps my options open for more powerful cans in the future. Hopefully I'm happy with the results, as it hasn't arrived yet.
 
A few months ago, I'd have slapped myself silly for spending that kind of money on what most would consider a negligible benefit.
What the hell have I gotten myself into? 

 

 

[Solrighal]

Yeah, I'm just getting into this whole head-fi thing in the last few months...but I'm just a young guy so I don't have the funds to go crazy.
I got Klipsch Mode M40 cans on a Boxing Day sale after Christmas and soon after picked up a FiiO E10, just to see if I'd be able to improve anything...it set me off on a very expensive little journey, let me tell you. I got the beyerdynamic DT990 Premium 250 ohm a week ago or so, and they're decent with my E10, but I ordered an O2-ODAC combo from JDS Labs a couple days ago, hopefully they'll drive them with a bit more definition. Also, it keeps my options open for more powerful cans in the future. Hopefully I'm happy with the results, as it hasn't arrived yet.

A few months ago, I'd have slapped myself silly for spending that kind of money on what most would consider a negligible benefit.
What the hell have I gotten myself into?   

I feel your pain. I've also just ordered an O2 and an ODAC from head'n'fi in Switzerland to drive my 2weeks old AKG Q701's. It's an expensive hobby but there worse vices to have.

 

[danivar]

I own the following amps and dacs and rate them as follows:

O2+Odac > Aune T1 amp+dac combo (w. Gold Lion tube) > Fiio E17 Alpen amp+dac combo > CmoyBB amp from JDS-labs (w. AD8066ARZ op-amp)
 
> = better than
 
O2 has more power than the T1 and isn't as bright. O2 powers my HD-800 very well, the sound is relaxed and spacious.
 
The T1 cannot push the HD-800 as loud (100% volume doesn't ruin your ears, which it would on the O2), the sound is a bit more congested and brighter – a bit too bright for HD-800 imo. The T1 works well with my K701's but the O2 is still better.
 
The E17 doest work well with neither HD-800 nor K701. The sound turns out very flat, dry and dull even thought it can push the volume pretty high. However, it works very well with my Beyer T5p and my Amperiors when used with the +12/+6db setting respectively. Sound is warm, perhaps a tiny bit dark, bass turns out quite full and prominent but can be turned down (or up for those who likes that) with built in EQ. E17 has a great battery, is very compact and is a pleasure to operate.
 
My CmoyBB is brighter than the E17 and doesn't sound as linear. It's fun and easy to modify. AD8066 is very detailed but not as balanced as E17. I had the 2227PA-chip earlier – it was too dark and sounded overall awful. 
 
Bottom line, the O2-combo is a great choice. It's the best sounding among all my amp+dac-combos, with all my headphones. However, it's not very portable (bulky and the batteries turns dull) works best as a desktop amp. For a portable setup i prefer the E17 (which I've heard is similar and better than the E10) which works great with headphones that are easier to drive. 

I ordered my O2-combo from Epiphany Acoustics in the UK (It works better with the stock cable than with their MJ2-cable, which just makes the sound brighter and more congested).

 

[Solrighal]

The E18 works pretty well too but I find it a tad bright when combined with my Q701's. I've just placed an order for an ODAC and O2. I'm very hopeful that will be a step up for me in sound quality.

 

[leithen]

For me, there was no comparison - ODAC+O2 was head and shoulders above the Fiio E10 (I have JDS labs variant and love it). With the build to order options, you can customize it which is nice as well (e.g., 1/4 inch jack).