Pros: Great mids/highs without being sibilant.Very comfortable to wear.Very fun headphones with warm sound.Amazing mids/highs detail
Cons: Not very deep and boomy bass. Creaky headband,Pads may start unsticking after a few years.Pleather pads may get hot.Brown color.Not neutral. Diff Vers
My pair had a very warm,smooth, lush and fun sound that was mostly mids oriented and had extended highs, but I didn't find sibilant. I much preferred it to the pair of SR-202 that I had before that was very UN-engaging. (translation - if you like neutral - get a pair of SR-202 or LNS) Like the pair of SM3 I own, the SR-404 seems to go well with nearly and kind of music I listen to with them. (SR-404 are even more detailed than CD3000 in the mids, but tends to be less harsh than CD3000 in the highs. My pair was 'warmer' in the mids than SM3 as well)
The only minor sq issue I have with them, the bass doesn't extend quite as far as top end dynamics (I had a chance to compare side-by-side to a Beyer T1). It's also boomy.
Personally, I prefer these to the vintage pro-bias lambdas, and you have more of an assurance that they're not going to fall apart or develop a channel imbalance, since they're markedly younger.
The only wear and tear issue I had was with my pad's double sided paper that holds them to the driver. The glue there gave up and the top of the pads stopped sticking to the body. Easily fixed with new double sided paper or new pads .
here are some pics:
please note, there are several versions of SR-404 depending on the production year. The sound is allegedly very different (according to spritzer and a couple more people) It seems it's very difficult to determine what version is FS, maybe only by year, not serial number. My pair was from around 2005.