Turning 5.1 system into 7.1

[Nessdufrat]

Hi guys!
Happy owner of an "old" Sony STR-DE635 amplifier, I recently changed my TV (went from CRT to flatscreen, ten years after everybody else), and I bought new speakers since mine were kinda crappy and my subwoofer had died.
I bought Bose acoustimass 10 series IV second hand (cheap), and I'm really happy with them (and yeah, I read lots of stuff about Bose, etc., but remember I had probably the crappiest speakers out there and of course everything sounds awesome after them). It turns out my amplifier isn't able to read the new sound formats. Anything newer than a Dolby Digital 5.1 either gets prologic surround or nothing at all. I didn't really care about that before because my flat is not the best place to watch movies using the home theater, but I'm moving in two months in a brand new building with far better sound proofing.
So, I'm buying a new amplifier (on a budget here, so second hand too. It's an Onkyo NR-616. I'm picking it up on Monday). It's a 7.2 amplifier, and I was thinking about maybe adding two more speakers to it, but I'm not sure it will work since the Bose speakers are connected to the subwoofer, and the subwoofer is connected to the amplifier. I guess adding two speakers to the amplifier will kinda mess things up with the Bose subwoofer? Sorry for my silly questions, I'm not an expert...
I already own two old Sony speakers, nice, bulky, heavy speakers that render music quite well, and until now, they were connected to my sony amplifier as "main speakers". The crappy speakers were for movies only. I plan on using them on the Onkyo the same way, from what I saw I can set two sets of front speakers, one set for music and one set that will be used for home theater (correct me if I'm wrong).
My question was about maybe adding two more "home theater" speakers to the amplifier to complement the Bose acoustimass system. Is it possible to do that?
Thanks for all advice!

(and yes, when I'm super rich, I'll definitely go for some JBL or B&W speakers, but for now Bose and Onkyo will do the job ^^ Sorry I'm defensive about that but I read a few posts on the forum about Bose and they were all about how people shouldn't have bought them, etc. I had a great opportunity on the Bose system, I used to have them at home as a kid and the sound was awesome, I asked a friend's friend for advice and his words were "if you can spend $1000, buy something else, but if you can't, just go for the Bose system because it's a good deal for your budget". So I did and I'm happy with the sound)

 

[markw]

For a cheap-a$$ solution you could connect your Bose 5.1 system to the receiver AS a 5.1 system (As per Bose directions) and connect the two new rear surround speakers directly to the receivers speaker terminals.

Now, how well it will balance out is anybody's guess but, since you're on a budget, ya gotta do what ya gotta do.

Maybe you can get Bose to sell you two matching speakers?

 

[WaynePflughaupt]

Maybe you can get Bose to sell you two matching speakers?

I checked ebay and its easy to find Bose speakers sold individually or in groups.

Regards,
Wayne A. Pflughaupt

 

[Nessdufrat]

Hi!
Thanks! I know I can find the Bose speakers quite easily one by one. I guess I'll have to make sure they match mine in terms of wattage and impedance.
I could always try first to hook up two of the crappy speakers to the amplifier to test how it would render "at worst", but I'm worried about the impedance. They are 4 ohms and 6W (Bose are like 8 ohms and I don't know about the watts since I can't find the info for the individual cube speakers). What could happen? (this would just be for a test before actually spending money on two additional Bose double-cubes)
I was mostly worried about the balance. I guess I'll be able to adjust the settings on the amplfier.