Aside from the pouch, you don't get any other accessories with the W1 bought separately. If you buy the bundle, though, you also get the replacement tips, tip cleaner, cable, bass and treble ports, and treble tip removal tool that come with the SA6 phones. The bass + port has also been updated to a new bass ++ which is meant to give a bit more kick to your bass lines.
Sound quality is largely determined by the SA6 earphones, which we do think are rather good with the cutting-edge extended-range drivers providing fuller bass than we're used to from a single driver design while maintaining an impressive level of clarity at the top end. However, there is definitely a very light background hiss added to the proceedings, by the W1, that could prove distracting if you listen to a lot of classical music with quiet passages (solo piano, quartets, that sort of thing) for instance. However, for the most part this hiss was masked by even fairly quiet track audio and also by the murmur of background noise that will inevitably leak through the phones.
One small complaint we did have was that when you plug the receiver into an audio source and also when you turn the adapter on it causes the headphones to thump and crackle (as audio devices tend to when you unplug or plug inputs), which can be loud and painful if you've already inserted the earphones. It's an easy scenario to avoid but does catch you out every now and again.
Overall, though, we really like the W1. Unlike Bluetooth headphones, the wireless experience can be used with any audio source, the receiver is very comfortable and unobtrusive, and the audio quality is impressive. The only real problem is the price, which at £100 is simply too much for us to outright recommend it. It's not extortionate but you should probably have a good long think as to whether you really need your earphones to be wireless.
The Sleek Audio W1 wireless headphone adapter is a great product and, whether bought separately or bundled with Sleek Audio's SA6 headphones, it is one of the best wireless audio systems we've used. You do, though, pay quite a premium for ditching those wires and we feel the price needs to drop a little before we could recommend them to everyone.