i've just got my t90 and they sound great on my iFi iCan Nano Amplifier , i was thinking of getting the iFi iDSD Nano because they look alike ( looking neater ) but im not sure if a dac is worth the investment and hope someone would educate me alittle more on how much does a portable DAC actually affect the sound quality ? 

Many DACs now come with Amp , but i got a great portable amp (to my liking) and i wish to get a DAC (alone) of size smaller than the palm . if you do have any recommendation of high performance to price ratio DACs please list down a few so that i may be able to try them ^^ 

i have permissions to try alot of portable DAC in the market  

Thank You !

http://www.head-fi.org/t/696401/giant-list-of-sub-200-portable-dacs-w-their-chips-price

i've read this thread but have no idea which is running on better chip from those number :s