With Kenwood's HTB-503 home-theater-in-a-box, you can enhance your home on an average budget without sacrificing your firstborn. To take advantage of surround schemes that use more channels than a 5.1-channel receiver offers, you'll need to chain-in an external amplifier. Theoretically, any THX-certified amp of equal power will work fine with a THX-certified receiver that has the appropriate line outs, but it's usually a good idea to stick with the same manufacturer—if for no other reason than the components look as if they're from the same family. Denon offers the POA-5200 two-channel amp ($699) as a complement to their AVR-4800 receiver. The 5200 is a THX Ultra-certified two-channel amplifier that delivers 120 watts per channel into 8 ohms or 200 watts into 4 ohms. It features a rear-panel jack for remote power-on/-off control through the AVR-4800. The 5200 differentiates itself from many stereo amps in that it's actually two mono amps in one box—each channel has its own power transformer and DC-storage-supply section. It also features A/B switching for each channel so that one or two speakers can be connected to each channel and can be turned on or off as needed. When testing the POA-5200 in conjunction with the 4800, I found no distinguishable sound or level differences between the two, proving that the 5200 is an excellent addition to the 4800 for bringing THX Surround EX to life.