A while ago I was looking to upgrade my portable headphones, as all I had were some Sony in ear ones that came with my MP3 player. So I did a bit of research about (not too much though) and ended up buying a pair of Sennheiser PXC-150 Noise Cancelling headphones. The following is my impression of the headphones after having had them for about 2 months now. 1. Design and Build Quality This is probably the biggest gripe that I have with these units as there are some major issues in this department. To start with the design of these units is similar to that of the PX series or the other PXC series headphones with a few noticable differences. The first difference to note is that while the arms of the headphones are of the same construction as other units, complete with notches to hold together when folded, they lack one major feature here - the hinge to allow folding. It appears that Sennheiser have decided to save the 5-10 cents the hinge would have costed by omitting it yet still having the same arms and earphone cup rotating part. This decision also seems to negate the purpose of being able to rotate the cups as the design of this mechanism is particularly weak and is the first point likely to fail. The second noticable design deficiancy is the choice of padding on the top of the headband. Instead of the padded leather (as seen on PX-200's) Sennheiser have opted for some form of cheap foam rubbber, which does not seem to pad the band effectively. Here's another $1 saved in production costs. Another problem can be found in the NoiseGard (lets not even go into that crafty trademark name) unit. It seems that this unit is excessively large and cumbersome for something that holds a small PCB and 2 AAA sized batteries. Similarly I must question the use of AAA bateries instead of a smaller rechargable unit that could be charged within the unit, although this could have to do with having to carry another power charger when travelling. 2. Sound Quality I am by no means an audiophile, yet I find some issues with these heaphones in terms of sound quality (mostly with the NoiseGard unit switched on). The sound production here is adequate with the NoiseGard switched off and produces sound equivelent to PX-200's, however with the unit switched on a few problems arise. Firstly there is a noticable increase in both volume and bass levels when switching this on. Whilst this could be assumed to be caused by the reduction in outside noise, I have checked it when in a very quiet room and produced similar results. What appears to be occuring is that instead of decreasing the level of outside noise, the unit is instead increasing the volume and bass so that outside noise is less noticable, which appears to defeat the purpose of cacelling noise as if I wanted it louder with more bass I would just adjust what I am listening to. The second point worth noticing is that the NoiseGard unit seems to very sensitive to mobile phone signals. I have sat in a train carriage with no one around me and had constant interuptions from mobile signals even though my phone is turned off (note: by interuptions I mean the noise you hear on a radio if someone is about to receive a text message). Another point worthy of notice is the levels of white noise that the NoiseGard unit produces. When switched on you will notice an increased amount of static in the quiet points in songs or in the gap between tracks. 3. Pricing In Australia these units retail for approximately $200rrp, whereas the PX200's retail for approximately $130rrp. This means that effectively you are paying about $70 for the NoiseGard unit. 4. Sennheiser Customer Service After I had used these units for a few weeks I had pretty much discovered all of the problems as listed above, and I thought that I would contact Sennheiser to inform them of my opinions so that they could make better products in future. I firstly attempted to contact them through there online form from theur website, which didn't seem to make it through to anyone as I received no response. I then decided to find contact them through direct email so that they were aware of my issues with the unit to which I finally recieved a response. This first response (from Marketing Operations / Customer Support) basically told me to go to their website (where did he think I got the email address from) and compare the products (already done, no mention of lack of hinge mechanism) so that I could find out the differences between the models. Further to this he suggested that problems with increased volume and bass had to do with me having a weird shaped head and not getting a proper fitting between the headphone and my ear. I responded to this email again outlining my problems with the units to which I got a further response. This second piece of correspondance gave me a list of all the parts (with part numbers) so that I could compare the difference between the PXC-150's and the 250's (which cost approximately $100 more in Australia). (The main difference between the two headphones were the earpieces and the headband, the PCB unit remaining as the same piece). I was then advised that I should have further researched information on their site which is not visible so that I could have better informed myself of why I should spend more money. In a further effort to make me go away I was then referred to the Australian distributor for Sennheiser so that I could contact them. I then decided to contact the Australian distributor and see if I could get a replacement headband as this would at least solve some of my more major concerns. I was politely informed that this part was not available, so I responded outlining my situation. I recieved and email stating that they wished to contact me directly, and so I provided my phone number and have not heard a word from them since. That was one month ago.