Looking to upgrade


Hello, I'm looking to upgrade my home theater system and was trying to figure out where to start. I was thinking starting with an old Lexicon DC processor and 5 channel amp. I don't want to spend an arm and a leg, but want to improve the overall sound over my setup which includes:

Original KEF 105's mains
KEF C100 center channel
NHT VT-3 surrounds
SVS PB12-ISD subwoofer
Marantz SR-18 receiver
PS3 for Blueray/DVD

Any suggestions would be appreciated.
teslaroadsters
Quick clarification on the Arcam AVR 350 recommendation. Charles is right it would take patience and luck to find one used, but people do buy and decide to upgrade quickly if they get the bug. The reason you need to have the AVR 350 is that the AVR 300 and AVR 250 do not have HDMI switching. You have to have this to run BlueRay through the receiver. The new Arcam AVR 280 also has HDMI switching. I'm not sure the price, but should be around $1700 or so.
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There is a hierarchy in audio/video reproduction, and speakers are not at the top of that hierarchy (indeed, just the opposite). They are very important, as is everything in the chain, but they can only play back the signal and reproduce that amount of musical information that they receive. Indeed the relative importance of speaker quality increases as the quality of electronics involved increases. I suspect if people think there are only modest differences between electronics (digital sources, preamps, processors, amps) they haven't had the opportunity to spend much time with truly good electronics.

There was a great awakening in Audio in the 1970's and 1980's. It was realized that the old thinking of speakers being first and sources/electronics being comparatively unimportant was exactly wrong. People sometimes refer to this as the "source first" philosophy. It remains acknowledged in its basic tenets today by nearly all audio writers I have read. It also remains one of the most fundamental but difficult concepts for people coming into the hobby to accept. I certainly didn't until personal listening experience demonstrated over and over again to my stubborn mind that it is unequivocally true. (That is of course, so long as you don't take it to silly extremes of equipment mismatching).

Now, as to the comparison between the Arcam and the Marantz receiver specifically, as Bob suggests, that can really only be settled by the purchaser doing a direct A/B comparison between the two, preferably in his own system. As to upgrading electronics first before replacing the speakers in question (which to do properly is going to cost more than the total budget anyway), I feel very strongly about that wisdom.
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