First of all , I do ALOT of research on canal\/earbud phone -lrb- include read all of these review and many other on other website -rrb- before settle on a pair for purchase . I be pretty much a audiophile however that do not mean I expect pefection with every purchase , I realize there be ALWAYS go to something that I wish sound , work or be design better . I be also a bargain shopper not willing to shell out $ 500 and up for headphone , mainly because I can not not afford it and I -lrb- like the rest of we -rrb- do not like be overcharge . that be say , let I start with that fact that I actually purchase the Sony mdr-ex51lp 's not the mdr-ex71sl 's . the reason ? after my research I discover there be not much difference between the 2 , save the short cord\/extension problem you will read about later and the fact that they carry they at best buy which make it easier to return they if necessary -lrb- I come across comment that state Amazon charge you if you decide to return the mdr-ex71sl 's -rrb- . let I start by say I be very satified with my purchase . I buy they about 3 week ago at best buy for $ 39.99 plus tax , roughly the same price Amazon be charge for the mdr-ex71sl 's . I be look for earphone that would block a significant amount of exterior sound , fit snugly in the ear and not fall out as well as produce a quality of sound I would appreciate . I can say all of those need be meet with my mdr-ex51lp 's . there be a few thing you should know about these earphone though .  # 1 if you do not like have to fiddle with little thing to get great sound , do not buy these . the multus size silicon earbud covering take a little time to figure out . you must have a complete seal to hear clear bass so play with the size to see which one fit you . I actually luck out and the medium size -lrb- which be already place on the phone -rrb- fit my left ear perfectly give I a understanding of how they should fit . my right ear be not so lucky and after play around I find that the large size be the solution . # 2 you must understand that these phone work like ear plug . you have to fit these baby snugly in you ear or the bass be not distinct and the noise around you will be more audible and not as cleanly `` block out '' . a proper seal be a must !! now this be not nearly as hard or annoying as it sound and once it be do you 'll be happy you buy these . as a side note , the silicon earbud can get quite dirty if you do not use q-tip often so clean you ear ! also this `` ear plug '' sensation will take some get use to -lrb- for I a couple of day -rrb- so have patience .  # 3 part of the complaint I note from other reviewer be the cord of the mdr-ex71sl , apparently it be quite short and design for ipod user and player with arm band capability . Sony 's solution be to include a excessively long extension cord that again apparently cause problem -lrb- read the rest of the review -rrb- with its connector . the mdr-ex51lp have the same cord design as the mdr-ex71sl 's -lrb- right side longer than the leave so that the cord can sit behind you head -rrb- save one distinct difference . the cord for the mdr-ex51lp have one long cord like every other pair of headphone you have ever own so it be much easier to deal with . however , due to the similiar behind the head design -lrb- right side longer than leave -rrb- , I do think purchase a clip be necessary to hold the cord in place . I find the extra length of the right side have too much slack and either get in the way or catch on clothing . this sometimes tug on the phone themselves , particularly on the left side . this become a nuissance . also the cord be pretty thin , no problem yet but due to experience in the past with other earphone I fear it could be in the future .  # 4 most importantly , be the sound itself . now this be where thing get complicate . everyone have different taste as how they music should sound so you be go to get vary opinion . I find , with a good seal -lrb- I can not stress this enough -rrb- , the sound be much improve over standard earphone and earbud . I find the eq a little tinny at first but the balance can be even out with a bass booster , this allow capabilty for heavier bass sound . my player have 2 setting of bass boost and I find the first setting to be more than adequate , the 2nd be a bit too much bass for my liking . the external sound around you disappear when music be play and this allow for quiet listening as not to damage you now clean ear . this be key as I travel alot !  so overall , I would say that Sony have do a great job . if you want really great sound with the small size and convenience of earbud and you be tire of tinny treble drive phone then these be for you . but if you expect pristine quality sound and bass that bump you out of you chair I suggest you stick with over the head headphone or if you be willing to shell out $ 500 + for the top of the line then go for it . Shure 's ec5 's rock . but I , I would rather shell out $ 40 for earphone that give I just what I be look for . if you check out comparable earbud phone you 'll find you 'll end pay more for very simliar result in sound and other trade off of various problem , etc. . I check out Shure 's -lrb- ec2 & ec3 -rrb- as well as etymotic -lrb- er-6 -rrb- and there be minute difference in performance and design but huge difference in price !! final word , I rate these only 4 star because of the cord problem and the weak excuse for a cord case -lrb- do not bother it be too time consuming and will break eventually -rrb- but I be extemely please with my purchase and would highly recomend it to anyone look for a reasonably price pair of high end earbud phone . however , I would seriously recomend the following : Research all , physically check out all and then buy what you prefer .