Pros: Sounds good with all genres.
Cons: Sounds slightly "grainy".
Found these classic headphones at my local thrift store for 20$! I just had to pick them up immediately when I saw them. Lucky I was, they were in perfect working order, and also cosmetically in a good shape.
When I first heard them, I was really surprised. Since they were "monitor" headphones I expected them to sound ear piercing, with little or no bass, but wrong I was. The AKG's have a natural warm sound with solid bass and plenty of detail.
So let's compare them against the 400$ Sennheiser HD600's, and see how they hold out?
The AKG's have slightly more oomph than the Sennheisers, but the nature of the bass is very similar; it has a nice mid bass impact, but is never overpowering. However I find the Sennheiser's bass to be tighter, while the AKG's sound slightly "bloated" at times. Both have a bass rolloff at around 50hz.
I find the Sennheiser's have slightly more "tight" mids, in a way they sound sharper, more accurate. Sennheiser also has the edge on instrument separation maybe due to this. The K240M sound slightly compressed in comparison.
I found the highs in the HD600's to be somewhat cleaner, more "airy" and sparkly, than the AKG's. AKG's top end sounds slightly "grainy" in comparison.
When compared with the HD600's, the K240M's don't sound bad at all, which is quite impressive considering the HD600's cost 4 times more.
This is just a quick review, I will edit this later. Now off to sleep!