Price Paid:  $90.00 from Pro Audio Store (Musik Alexander)

Summary:
I purchased this headphone with a whole PA System for a church to have a closed phone for monitoring.
The HD 270 fulfill this purpose well, although they don't isolate as well as Beyerdynamics' 770 Pro for example. That's not a problem in my case as the mixing board has a strong amplifier for the headphone-jack build in. If did have to use the HD 270 with lower powered systems, which would have required a separate amp - I couldn't really hear the signal, especially at high sound pressure levels from the main PA. I find the headphones comfortable to wear, although they tend to heat up the ears after a while (but they're closed headphones, after all).
As for sound, I think they sound good enough for monitoring purposes (live-sound!).
If you want to listen to music (private), you'll find that the bass freqs are quite loud. I don't like that all the time, other people may prefer just that.
One time I used it for mixing in a studio. Big surprise, you tend to mix a lot less bass into the recording. For studio use I would recommend more neutral sounding phones (I prefer the Beyerdynamic 990 Pro).
By the way, I bought an E-Drum set recently and I really like monitoring with the HD 270, just because of the strong bass - it gives a good feeling of the bottom end.
Though I own and use more expensive headphones and could buy more expensive ones for PA monitoring, I think the HD 270 does its job well enough and it is definetly worth the price (I bought it in Germany - don't know about other prices). It's comfortable and loud enough. For home I'd use something else, although it's alright to listen to records with it, once again if you like bass. I don't think these headphones are suitable for studio monitoring.
The best thing to do: Try them and see if they work for you!

Similar Products Used:
Beyerdynamic 990 Pro, Beyerdynamic 770 Pro

Price Paid:  $150.00 from Stellar Stereo

Summary:
I really love these headphones... I really do, however, I paid too much, I admit it. BUT I think that they are worth it. They are quite durable (taken them a lot of places, unfortunatly) and comfortable, except for the heating up of the ears as mentioned before (gotta take em' off sometimes it get's so hot!) Anyway, I think that they are good phones, but the 200's had much better sound, but the price was ridiculous, can't remember now but too much. Your ears with guide you on this on and your wallet secondly.
(4 stars on overall simply because I just love them so much... I guess their sound just really works with somethings...)

Strengths:
Say it again... Bass...

Weaknesses:
Umm... bass, too much at times. Can get muddy.

Similar Products Used:
Senn. HD 200

Price Paid:  $77.00 from Sennheiser USA

Summary:
These headphones are great for DJing and dance music production. They are much lighter compared to the Sony MDR-V700s which makes them much more comfortable to wear in prolonged sessions. And for about $70, they are a great deal.

Strengths:
Good Bass Response...

Weaknesses:
Looks cheap compared to Sony.

Similar Products Used:
Sony MDR-V700DJ, Audio-Technice MFH-40fs

Summary:
I got these headphones (the Evolution 2270s which are the same) last October because I wanted to get an upgraded closed headphone from my Koss R80s. These are an upgrade but VERY minor which means they are way overpriced. I got the Beyer 250s two months later and they BLOW away these senns in every which way yet they cost just a tiny bit more.

The Senn 2270s/270s do have decent bass but the rest of the sound is lacking BIG TIME. The highs are somewhat shrill and the midrange is lousy. You really miss out on alot of details/little sounds when using these headphones. Listening through these headphones, it sounds as though the music is under a pillow. Very muffled.

The Beyer 250s are everything the 2270/270s should be. They have a great soundstage, are very clear and just reproduce sound in a very pleasing way. It really isn't even a comparison.

If you're looking for a closed headphone around this pirce, please fork out the extra bucks and get the Beyer 250s or look for something else. These Sennheisers are just flatout not worth it. They're more like $60-70 phones.

Strengths:
Fairly comfortable
Decent bass

Weaknesses:
Sound is too muffled & muddy
Overpriced

Similar Products Used:
Beyerdynamic DT250-8, Koss R80, Sennheiser HD600 (but they're a totally different animal)

Price Paid:  $73.00 from sennheiserusa.com (refurbished)

Summary:
I bought the HD270 a week after I bought the 535, and my review might be colored since I am absolutely in love with the latter pair. The main reason I purchased the 270 was to use them in my lab, as I listen mainly to classical and didn't want the sound of freezers or centrifuges to come into a pause in a piano concerto. Sad to say, the HD270 phones do not keep out noise that are of this level.

Even at 5N, they are comfortable to wear for long periods of time. My only complaint on this part is that my ears tend to get quite hot after some time.

The sound reproduction of the 270 is very good, better than I have heard on most phones except the 535. However, it does not compare to that of the 535, though the specifications for the 270 look equal or better on paper. This might reflect the general dictum that closed dynamic phones are generally inferior to open dynamic ones. The bass gets a LITTLE too muddy, and often tends to cloud out the mids. The treble could be a bit brighter.

At 63 ohms impedance, I would assume that they could be coupled to portable devices. However, I find that I need to keep my portable CD player and my music system at higher volumes to get the same volume for the 270 (as compared to the 535, which have an impedance of 150 ohms).

On the whole, these are good headphones if you do need closed phones (especially for the price I paid). I plan to ask Sennheiser about the idiosyncrasy of the volume levels. Their customer service is exemplary (which is one of the reasons I opted for the HD270 over the Sony MDR V600 or 900).

Recommended, with reservations.

-MP

Strengths:
decent bass
reasonably comfortable

Weaknesses:
can be muddy in some situations.
moderate highs
do not really keep sound out
the headphone jack is finicky

Similar Products Used:
Sennheiser HD 535
JVC HAW300 wireless (cannot be used for music!)
Other non-descript panasonics etc