Missed the part that you need a desktop amp Honestly if you're looking for desktop amp, might as well as get a new DAC/AMP combo.
Anyway for the Cayin C4 sound signature, airy and detailed, very transparent and a hint of 3D like spaciousness. Better than E12/E18. You could use it while charging but be noted of the increased heat during that.

If you would like to compare the AMP section entirely, definitely the Cayin C5. Aune T1 is a DAC/AMP at which the tube is being used in DAC only, you wouldn't want to use your UD110 with it.

What headphone you're using with your Fiio E07k? It might be that you're overestimating your E07k, did you a/b compare with your computer too? (Same song and headphone)

If you plan to upgrade your DAC soon, or stress portability more. Definitely the C5. The UD110 will bottleneck the C5
Aune T1 is like a whole package, if soon you want to upgrade, you need to change whole thing.

Another thing to be consider is to get a C5 first, then Aune T1 for home listening (Aune T1 DAC -> C5 AMP)

Your budget?

I tried the topping myself, it has audible distortion that i don't like at all. Nothing can change your sound signature in a large scale unless you change the entire headphone. Never expect large improvement over DAC/AMP, cables, plugs.
Do you have a DAC beforehand you getting yourself an AMP?

Stoner Acoustic UD120.

This post has been edited by psychoactive: Dec 17 2014, 05:43 PM

Which NAD do you own? the D3020?

AKG K7xx series is sort of power hungry, but it needs the correct DAC/AMP combo to let it sings.

IM02 is quite picky for dac/amp pairing, be sure you can try them first out before you buy.

HP150 has less sensitive and rather medium impedance, your IM02 has low impedance and medium-high sensitivity.
I don't recommend you getting the DACport, its ok for your HP150 use case but for the IM02, <1ohm is recommended else the sound quality will be affected and there will be distortion due to the electronic damping issue.
LX mod? It's an version of DACport, by removing the volume control and providing line stage output to your amp, if you have already an amp and gonna connect your DACport LX with it, go for it.

I don't wholeheartedly recommend the DACport just because of your IM02, even with 1ohm mod.

I use a Topping NX1 + UD120 via OTG for my Havi, damn damn good.
You can try to look around for a used UD100/110 either.

the new and powerful,, Cayin C5.Hardly any DAC/AMP combo, unless you go separately. on the side note, did you get yourself LX version? if that case, you would want to get an amp.

You're welcome. Yes, at first i was skeptical about it too, after listening to it, I was astonished how good it is, not to tell the price/performance ratio too.

Fiio E07K (a little more budget), but it doesn't have good synergy as the NX-1 does. Or maybe you can try to raise the budget for a little (300?), it's worth any penny to get a better amp for your Havi. (I have ran my havi thru Yulong D200 before)
Or another alternative way is, just get the UD130, and use software volume control.

This post has been edited by psychoactive: Apr 20 2015, 12:01 PM

From what you got, it's not day-night significant but definitely you can listen to the audible difference. Sounds get clearer, smoother, treble extends better and bass get deeper. You can always try to play with the lower end budget models.
If you're getting an AMP, I recommend you get a line out adapter, and to connect your iPod touch to the AMP.
DAC/AMP combo for apple device costs a lot. (proprietary) Like the Fostex HP-P1 i'm selling.

Of course that I didn't know your budget since you didn't state it. IMO, everything > 500 is considered as low-mid, and >1000 is around the mid-high part. That's a quite medium budget. If you would like something more portable (lets say a DAC/AMP combo FOR apple devices), it's easily can go over >1k over the price. e.g. Centrance Hifi-M8, Sony PHA-1, PHA-2, V-MODA Verza and more.
On the other hand, I'm considering letting go my HP-P1 <1k, you want it?

Desktop - O2 (save abit)
Portable - Caiyin C5 (extend abit)

For that budget... not much choices, but can't go wrong for the UD120

Your budget?

No budget ->

Think of it as a analogy, lets take car as example, DAC is your engine, AMP is the electronic components which controls the whole car in conjunction with it in work, convert power into performance.

Imagine if you're implanting a lousy engine into a Ferrari, it will bottleneck the components, and vice versa.
It's better to balance it in term of performance and SQ for both DAC and AMP.

Source? but idsd doesn't have as much features as the hugo has

for the reason.. we know why that's the true way of 'audiophilia'.