|Plus they will be for portable use WITH MY minidisc, since I have speakers at home, which will always, (in my opinion be better than phones)|
|Well I will be using a Creek Headphole AMP fwith the minidisc to power my phones.|
Also, unless your minidisc player has a line-out (mine doesn't), you will not get the benefit of the clean power an amp can provide. You'll merely be amplifying the noise of the cheaper amp inside the minidisc player.
As for you question of whether the SR-325 is worth the extra $200 in comparison to the SR-80, all I can tell you is that there is a world of difference between the two 'phones. The 325s are fuller, richer sounding headphones. In particular, the bass is tighter and deeper. The soundstage is deeper as well, due to the increased size of the earcups. Only your ears can decide if all that is worth $200. To me it was. Good luck.