Dont want to talk about mask. Covered already.
But, do not put subs in the rear shelf it will sound terrible I promise. They need an enclosure plus you will struggle to make them fit without serious metal cutting. If you are after quality then eights are the way forward but free air will not do the system any justice.
By biamping I assume you mean using four channels of amps to actively run the front components. If this is the case I would advise against it. It will offer you more power than a standard passive crossover running off two channels but you will need to use alternative capacitors to create the necessary hi and low pass filters. Seems like a lot of effort for little gain. Better to buy a decent two channel and run them passively or even a four channel and run them actively with an electronic active crossover. Be warned, active front ends are much more difficult to get sounding right.
I personally have imported amps from the us. Uk importers will complain and tell you that when they go wrong they will not service them. Big deal, so you pay the ten pounds and ship it back to be repaired in the states. For this you pay about half price. I know what I'd rather do. Try ebay.com and search the make you want, you will be upset by the cheapness.
I would advise phoenix gold or soundstream. Orion are also fine sounding.
If you are going to do this, then try to spend as much as possible to make the effort worthwile. Also you will make a bigger saving on a more expensive product.
The other option is to buy second hand as second hand quality items will sound practically identical to new products.
I know a way of getting cheap american made amps in this country, if you are interested email me directly.
