Howdy head-fiersAs you may or may not realise ... sennheiser have recently released an aluminium version of the HD25 - not to be confused with the amperior.The Aluminium version has been released to celebrate 25years since the original HD25 was released in 1988. The amperiors were quite popular with their low impedance drivers and remote / mic cable but according to my sources in sennheiser they did not sell quite as well as they initially hoped - possibly due to the fact that they were not ideal for pro use which was always the HD25's main market.I have dismantled, tweaked and modified literally thousands of pairs of HD25-1, have a deep love for them and know them inside out - so when I got a visit from sennheiser in feb to tell me all about the new versions I could not wait to get my hands on them.I was told at the time that there was potentially 2 new versions on the way the aluminium and a larger earcupped version. When Frankfurt came around the HD25 was finally released ( still no news on the the possible larger version - may be delayed or may be vaporware )The HD 25 Aluminium are very similar the the standard HD25 Pro with a few nice tweaks. The have the same 70ohm pro drivers as opposed the the 18ohm ones on the amperior so should be compatible with high end kit that prefers a bit more impedance. The obvious change is the earcups which are milled from a single block of aluminium, this is not just a cosmetic change, the extra rigidity and weight really help to improve the sound. In my experiments with the HD25 I found you would tighten up the bass and help bass extension by adding mass to the back of the driver and these heavier earcups do a similar job ( i posted my mods before they released the amperior so I like to think they copied me LOL ). Another improvement is that they have new pads - the new pads look and feel nicer than the original HD25 pads. They look more like real leather ( not sure if they are ) and feel more like some of the memory foam pads I have used so they are more comfortable and make a better seal on the ears - the headpad is also fatter. Other minor things .. The have the silver aluminium flatter hinge covers from the amperior but one thing that I did not like was they have started using t6 screws rather than the more common philips head on the cable clamp which makes it less easy to replace the cable if you need/want to.Sound wise.. After letting them run in overnight I had a good A vs B listening session with them. They are very similar ( they do have the same drivers ) but the new aluminium are definitely a a bit warmer and richer than the normal HD25 and they drop off less at the low end - you can hear more of what is going on in the sub bass frequencies. So if you love the HD25 but want something more sophisticated and with deeper richer bass then these are just want you are looking for. They also come in a nicer padded box and come with a nice zip up case to keep them in ( a bit flimsy but nice looking)Obviously another good thing is that they will take all the many accessories and upgrades the standard HD25 have available so there is still room to squeeze a bit more out of them. If you skip to about 5:00 in this vid you can see them with a little sided by side against the hd25 http://www.youtube.com/watch?v=pT4HCc8DPSI If you have any questions no matter how techy just ask