Umm, did you buy those headphones new?Raymond Lin said:I dunno if you can still get them now but i got my Sennheiser HD580 for £55 a few years ago. They were £200 rrp when they first came out, and also got a pair of HD600 for £120 (these were £350 !). For the money i've paid for them, they beat everything under £100, they get even better with an amp.
Personally i would get open headphones, i never got on well with closed, always sounded contricted and too boomy to my liking. The Grado SR60 or may be SR80 might be within your budget, which i would think will be great and better than koss howevere you do pay for it.
AFAIK, they the HD580 still routinely go for closer to £100, and the HD600 £140-ish. As for whether they beat everything in the under £100 range, it still depends on your preference really. The Grado are too different to compare to with Senns. It is possible for someone to dislike the HD600/650 yet like the Grado SR60 (or vice versa). And having tried the AKG K501 with the Senns side by side, I don't actually think the AKG necessarily lose out. Yes Senns wins in terms of bass, but for soundstage, the K501 are pretty much reference class (great mids too).
I won't argue that the SR60/80/MSi are better than the Koss. They better be, considering they cost nearly twice as much. And yes my Porta Pro has been gathering dust since I bought my HF-1 (6x the cost). That said, the Porta Pro are more confortable than the Grado (which aren't known for their confort), and you can't really go wrong with them IMO (whereas you could with a Grado if the sound signature is not for you). Still, keeping in mind the OP has £100 to spend, I would suggest that he tries at least the Grado/Senn (and preferably the Beyer /AKG/AT too) if possible.
And lastly, I agree with your impression on closed phones overall (some are better than others though).