The Sennheiser PXC450 are average headphones with good audio reproduction and decent build quality, but questionable design choices. Unfortunately, the noise isolation is severely lacking and is not recommended for use in noisy environments.
The PXC 450 make poor everyday headphones. Their sound is decent for a bit of critical listening, but they are not comfortable and too bulky for everyday use.
Mediocre for critical listening. They have an adequate frequency response but a poor soundstage because of their closed back design.
Poor for commuting. Their noise isolation performance is decent enough for moderate levels of ambient noise.
Not designed for sports use. Although they're moderately comfortable, they're bulky, cumbersome and too unstable for sports headphones.
Poor for office use. Noise isolation is not enough for the chatter of a busy office. They're also quite leaky.
Average for Home Theater use. They have no latency since they're wired and have a sufficiently decent sound for movie watching. However, they have a relatively short audio cable so unless you have an extension cord they won't be ideal for comfortably watching movies from your couch.
The PXC450 are unremarkable in their style. They do not look as premium as the Sony MDR-XB950N1. The large gray ear cups are accentuated by the silver highlights of the buttons and Sennheiser branding. The headband, as well as the cushion of the ear cups, is coated with a soft black padding. The sliver of the metal at the hinges and the frame add a little more style but not enough to make the PXC450 stand out.
The large earcups are decently padded and mold well to the head. They are very large though, and may be a little too massive, depending on the user's head size. The PXC 450 would be a lot more comfortable if it wasn't for another odd design choice: The inside of the ear cups protrude outwards and touch the listener's ears, if not placed on the head perfectly. This causes a lot of discomfort after long listening sessions.
Button layout is average at best. The buttons are functional but just poorly designed and feel cramped on the very large ear cup. They offer volume and "talk-through" controls but no play/stop button. There's also a strangely hidden switch on the left ear cup that just adds to the oddness of the button layout.
The Sennheiser PXC450 are decently stable headphones that stay in place during casual listening sessions. They are not designed for sports, though and will quickly fall off your head during high-intensity exercises. On the upside, they have a detachable audio cable, which helps reduce the chances of the headphones falling off your head if the cable is caught on something.
The PXC450 are on the larger side for over-ear headphones. The big earcups lay flat to be somewhat portable. Unfortunately, they will take a decent amount of space in a backpack. They won't comfortably fit in a handbag and are far too big to fit in any pockets, even larger jacket pockets.
Comes with a soft case that will protect the headphones from scratches and minor falls. However, the case adds a bit of bulk to the already large headphones. It also won't shield them from water damage.
Build quality for the PXC450 is somewhat decent but has a couple flaws. The headband and ear cups are well-padded and the metal frame adds a little more sturdiness to the build. Where they lose points is with the build of the ear cups. The plastic looks and feels cheap, the inner earcups stick out and touch your ears if the headphones are not placed perfectly and the battery compartment is placed awkwardly.
Update 03/05/2021: We've corrected the Detachable test results from 'No' to 'Yes', as these headphones have a detachable 1/8" TRS cable.
Poor noise cancellation overall. Passive isolation is decent, about average. There seems to be a little bit of build-up happening in the 300Hz range though. Passive isolation starts at around 500Hz and reaches -30dB at 5KHz. The active noise cancellation doesn't do a lot, offering less than 10dB of reduction starting at 100Hz up to 600Hz.
Decent leakage performance. The peak of the leakage is in the high-mid to low-treble range.
The PXC 450 provide up to 21 hrs of continuous play time. They are decent headphones to take on a long flight, but you will have to keep a spare AAA if you don't have access to a store while on your trip. Unfortunately, they also do not have any battery saving features like an auto-off timer and can't continue playing audio passively once the batteries are dead.