Can PS3s math the audio and video quality of a Blu-Ray player?

What's an "HDMI lead"? Are you talking about an HDMI cable?

The more you pay the higher quality the audio and video get, right?
Not in the case of HDMI. Well, there's different versions/types of HDMI and you'll probably pay more for an HDMI cable that has the bandwidth to push through 3D Blu-ray data (i.e. an HDMI 1.4 cable) than one that'll work with a conventional Blu-ray setup (1.3 and below), but in general, a cheap HDMI cable will perform just as well as an expensive HDMI cable. That's because of the "D" in "HDMI"--it's digital, which means that the signal coming through is coming through perfectly fine, or noticeably broken; there's no "softer" and "fuzzier" for weaker signals.

I just thought about the HDMI leads, and don't PS3s have one HDMI lead?
So?

So picture-wise, there should be no difference between a PS3 and a standalone Blu-ray player. Audio-wise, I'm not completely up-to-date as to what different audio formats the PS3 decodes internally and/or outputs directly, but I think that for most consumers, it's really six of one and half a dozen of the other and only the most discerning audiophile might care about the difference.

The PS3's a pretty robust computing machine, and at least back in the day (if not currently) it was more powerful than any standalone Blu-ray player. Even a PS3 from 2006 can play Blu-ray 3D discs, something dedicated Blu-ray players had to be specifically made to do.

The only thing PS3 can't do is play lossless Dolby TrueHD on 3D titles. There are only 5 3d titles with TrueHD sound, though.Almost all of them use DTS-HD Master Audio, which it handles fine.

Like commentaries? http://www.ratethatcommentary.com/

The component output is limited to 1080i for Blu-ray due to concerns about copying. Whether that's visibly worse than 1080p, I don't know. But I figure there must be some loss going from digital-to-analog and back again, compared with a straight digital to digital connection like HDMI.

Hmmm, quality of cables make no difference, really? Perhaps a demo at a decent specialist (not currys!) might change your view. If not, maybe an eye test might?

You evidently don't understand the concept of a digital signal. We're talking about HDMI here--it's all ones and zeroes. As long as the ones and zeroes are getting from point A to point B, it's going to look perfect. If they're not, then the picture will look noticeably broken. There's obviously going to be differences in build quality, and, as technology advances, standards (i.e. an HDMI 1.4 cable is designed to handle more data than its predecessors, to accommodate the additional bandwidth required by 3D Blu-ray), but in the realm of HDMI, it either works perfectly or it doesn't.

So how is it that you can clearly see picture quality differences between different hdmi cables?

Because you're imagining things.

Again, DIGITAL is DIGITAL. The devices are transmitting and receiving ONES and ZEROES; there's no such thing as receiving a ".5".

Saying one HDMI cable will yield better pictures than another is like saying one printer cable will yield sharper looking printouts than another. It's simply not true.