wow. looks like we're all into room acoustics all of a sudden! i was going to suggest the same, but randy pretty much covered what i was going to say about that.
one thing not mentioned: component vibration mitigation. there are many different methods: roller blocks, springs, cones, spikes.. do a bit of reading, there are some great threads on here. a simple and cheap method is to simply buy compression springs capable of supporting your component (weight of component/#springs = spring load needed) and stick them under the component. your turntable and disc player would benefit most from this, your amp less so since it's solid state.
dare i even mention this?: a decent power conditioner or powerblock and some good power cables can be helpful. powercords are very easy to DIY..
one thing not mentioned: component vibration mitigation. there are many different methods: roller blocks, springs, cones, spikes.. do a bit of reading, there are some great threads on here. a simple and cheap method is to simply buy compression springs capable of supporting your component (weight of component/#springs = spring load needed) and stick them under the component. your turntable and disc player would benefit most from this, your amp less so since it's solid state.
dare i even mention this?: a decent power conditioner or powerblock and some good power cables can be helpful. powercords are very easy to DIY..