Someone asked me to compare the Pro80 and the HI2050. Maybe someone else is interested as well so I leave it here also:
Finally got some time to sit down with the Pro80's and the HI2050's.
Let me first say that both of these are great headphones at their respectively price. Iirc correctly I paid less than $80 for both, pretty amazing.
The closed Pro80 naturally has better subbass extension and impact but the difference is not as big as one might expect. I do feel that the bass on the Pro80 is a bit tighter and less boomy (better quality) also. The HI2050 has more mid-bass bloom while the Pro80's sound very clean and clear.
Surprisingly enough the Pro80's are also a bit brighter sounding and because if this feels more energetic in its presentation. The Pro80 can also sound slightly hollow in vocal reproduction occasionally (something I find typical for closed cans so they're not worse than any other in this aspect). Treble extension is quite similar on the two.
Soundstage on the HI2050 is naturally better (due to them being half closed) but again the difference is smaller than one would expect. Although the HI2050 has a more airier presentation the difference is not big.
In all these are quite similar sounding so the differences are by no means huge (after all they do use the same drivers). The biggest difference is definitely in the bass and with some music without prominent bass they sound almost identical (with the Pro80's being slightly brighter).
Build is very similar but the headband on the Pro80 is of better quality and feel more sturdy.
If I had to pick a winner I'd go with the Pro80's because of the less intrusive mid-bass and better headband, others might choose differently though. I seriously doubt anyone would love one and hate the other, they're way to similar for that.
I usually prefer open headphones so this is quite an surprise to me.
Also, the price for less mid-bass on the Pro80 are a bit less full male voices.
Please note that I use both with Brainwavz HM5 velour pads.