Pros: Quit neutral, very good soundstage
Cons: A bit fragile
They are exceptionally comfortable and light; when I wear them I sometimes forget they are in my ears. The quantity of accessories is more than enough, though the quality of which is not so. The tips seemed poorly made, and one of the bi-flanges even has some defect. I only found the olive-like foam tips to sit snuggly in the ear canals. Isolation is above average with those tips, but the sound would be darkened because of that. The cords tangle quit easily such that I had to separate them almost every time, but this problem improved after more than a while.
The soundstage is wide and airy, which is probably is the most noticeable aspect and one of the main selling points of PL-30’s. Bass is tight and controlled, yet light as well. With a lot of burn-in (100 hr mark), bass is even tighter, and better quantity-wise, still incomparable to many. Another feature of the PL-30’s is the adjustable bass knob. When pointed inwards to the strain relief that’s called deep bass, whereas clean bass when pointed outwards. Most people would prefer the clean bass, as everything is less-veiled. On the other hand, deep bass made little changes to the bass impact. The higher range is never harsh. I find the mids and highs well defined and likeable. The depth makes you feel near the stage rather than someone singing in your head. Like many budget IEMs, ultra-high treble is rolled off, which means anything above 12000Hz is inaudible. That's not really something of significance to the average consumer as the highest fudamental note that an instrument, namely piccolo/piano, can play is just about 4000Hz, anything above 6000-8000Hz is just harmonics.
PL-30’s were first introduced as Shure E4C equivalents, which is something many would disagree upon. I personally think the PL-30 could have been over-rated to some extent because the popularity died out after the initial spike. They were nevertheless one of the better valued IEMs around early 2009, since then there has been a lot of competition rendering PL-30 not as highly competitive before. This is not to say PL-30’s are no good, on the contrary, for about $25 they offer balance, detail and a massive (for the price) soundstage.