Hello, I searched the forum but couldnt find the topic related to my problem so I'm going to ask for advise from audioholic experts. I have 5.1 HT system driven by Yamaha RX-663. Now wife wants to karaoke on it

! I know HT systems arent meant for karaoke. So what do I need add/setup I can still watch DVDs and wife can karaoke (without killing my HT speakers

)
In the mean while, I was looking at this system
http://www.vnnmall.com/product_info.php?cPath=179&products_id=4698
With this karaoke system, I guess wife can karaoke without issue correct? Now, can I combine the 2 systems or its a no no ? Something like this:
Yamaha RX-663 ---> 5.1 HT system
BMB MA-3000KII (Mixing Amplifier) ---> new karaoke speakers
Yamaha RX-663 ---> BMB MA-3000KII (yes/no ?)
Thanks in advance for all the inputs.
ND