I still question this Headamp.
 
Build qualilty looks good (the inside i dont know about) but still it's just another "made in China" casing.
 
There are several other headamps from china in this disguise... Argon is supposed to be HIFI klubbens own brand.
I have a feeling that the only difference between this ha1 and other headamps looking the same are the name on the front and the power supply. 
 
Talking about the power supply (220volt one) IT's HORRIBLE. you feel it right away...plastic on this regular looking powersupply is so poor quality that it breaks just by looking at it. I have never really moved the power supply around but allready the cord is loose, plastic casing is cracked, and the outlet is about to break. all of this by being safely hidden away and treated like a baby.
 
My guess is that you can find this amp for a much less price from another china brand. 
 
Sound quality...well it drives my HD650...and thats about all i have to say about that. 
 
I would NEVER buy this one if i did not need the extra power to drive hd 650 and to avoid to turn on my amplifier just for listening to Headphones (im one of those save power where ever i can type of guys).
 
 
 
 
 

 

My trust in Sennheiser is gone

 
For more detailed review on the sound itself there is alot of other really good reviews..this review focus on value for money.
 
Short said... Don't buy
 
 
 
Been a fan of sennheiser for many years...my trust is now completely gone!!!
I own 4 pairs of sennheiser, HD650, 595 and two pairs of in-ear... always use my HD650 at home and the in-ears when im on the move. 

A few years back i spend money on a pair of hd 595's to use on the move but never really used them because the in-ears is easier to carry with me.
I put my 595's in the 650 casing where they have been for two years since i dont use them. The 595's are as new... the cord has the same folds as when i brought them... even the new smell is still there.
The other day i decided to give them a try...and so i did.
I noticed a faulty resonance in the left driver so i opened them and found to my surprice that the driver was not in "shape" so i carefully corrected the driver. It turns out that it was not the cause of the problem... the driver was simply defect. 

Since the 595's was as new i decided to search for a new driver for them... and hopefully free of charge from sennheiser since i never used the headphones (even the 24 months warrenty is over i would expect sennheiser to deliver free of charge as good costumer service since this clearly is defect caused before it was packed)
I searched the internet for a spare driver and found posts from people with same problem. 
Also found out that my Sennheiser 595 headphone holds same driver as hd555!!! only difference is that sennheiser adds a piece of foam in 555 to block some of the frequency. So if you remove the piece of foam on the 555 you get a pair of 595. 
On top of that i find the build quality og 555 to be better than 595. I allways had the belive that the money spend extra on 595 was put in the drivers... not true!!! Sennheiser cheats.

This link clearly shows the driver is the same:
http://mikebeauchamp.com/misc/sennheiser-hd-555-to-hd-595-mod/

Been told that the price for the 595 driver is higher even its the same driver as 555!? which means that sennheiser is selling the same driver at two different prices.

Have always recomended Sennheiser to my friends etc. but that is now in the past. MY TRUST IN SENNHEISER IS COMPLETELY GONE.

To correct...Sennheiser now sells the 555/595 driver at same price....57$ each!!!!! that's 114$ for a pair of  spare drivers (without shipping)!!!