Maybe...you need a stander headphone amp first.... actually,in my experience , x-fi is not good enough in headphone output (neither for sr60 & k81dj)

switch 325i's driver to rs1's ,maybe you can get a nice sounding.... like HP-1000!?? I dont know , but I will give a try next week~~

plus 1 Hd280 and akg 271s cant fit well with protable device... output is too week to drive these headphone~~~ yeah, you still can hear something, but maybe lack most of detail.

It's also a broblem of mine,caz I still want to find something protable , isolation well,easy to drive,which I will use on HDV-cams. These device ,with headphone output ,are not build for hi-fi & full size close back headphone. May I use er4s on these device which can drive er4s good...

HD 280 is a nice gig ,close back one,compare with his price tag. However, this baby need an amp to drive it well , in my experense , there was no protable device can done well..

+1 er6i

I think you may need an amp for 24os , caz it will improve a lot in detail! since I use 271s / 240s for two years , for mixdown , it is better to use an amp than not. caz the more detail you hear , the more things you can handle. seriously, although I use them on the pro dat / cd...

SR-225 is a nice headphone , easy to use for any source without amp. but i will recomannd you grado ra-1 for amp when you want to upgrade next time,you will love it! I use grado for many years ,325i and hP-1000, nice gigs!

k14p...nice gig! I just bought it with sony mp3 to my mother for gift. Before I gave them to my mon,I try K14p with my tascam cd401 wow~nice sounding quality at this price!

I think AKG K271S with cardas cable is also a good choice for work.