Do I need to amplify all of my channels?

Your Mac seem to be a bit wimpy in the area of reserves (judging by the specs), so if you want to use it for the surround channels ONLY and you don't crank it up for extended periods you should be okay. Not great, but okay. Your front 3 channels need more power. 3 channels of Mac amplification would fill your bill (look for a Mac amp that double its' power rating into 4 ohms. Example-100 watts into 8 ohms, 200 watts into 4 ohms)

When you do the AVR settings (level, delay) do this at your typical listening level and your levels should be balanced.

Your best, though not least expensive option would be to get a higher power Mac driving all 7 channels.

Alternatively get a high-end 7-channel Marantz amp. For a (mainly) Home Theater rig this is likely about as good a compromise (cost/performance) as you'll get. IMHO.

your very nice B & W's deserve some more power. I would buy a good Mac Amp (MC 2255?) for your 803's and use the PreOuts from your processor. Use the processors power for the center and rear speakers.

Srwooten

Thanks for the thoughts, yes the MHT100 is a bit of a wimp. When it bought it, the MHT was a great compromise for me - excellent quality, but not separates. I knew that I would eventually add an amp and still have a great processor - that time has come. I am leaning toward 7 channels as my room is wired for such and the MHT produces 7.1 if it is offloaded to an amp.

Is there any particular logic related to amps whose power doubles into 4 ohms? Are there particular Marantz models recommended?

Also, I am not opposed to a used amp, in fact, I may go that way - I know there are several bargains (quality versus price depreciation) in older models.

Thanks
Mark

your room and listneing levels should give you an idea on your power needs.... However, generally speaking, having BW about, think of power, as your friend. your best friend.

Certainly speakers need power. BW speakers do well with a lot of it, I've had 5 sets.

I don't feel it necessary to stay 'same - same' with processor & amp either. With speakers, that approach works indeed, across the front 3, with rears & surrounds, mattering much less.

Assuming here you have a processor - AV multi ch preamp, or receiver on hand and further, it has main pre outputs, DEFINITELY adding an amp is IME a necessity with BW.

As to how many channels? you pick. Flavor? Again, that's on you too. Figure EVERY ch in the amp will drive one speaker and the proc will drive the powered sub. Simple.

I'd look for a smooth top end in whichever amp first. Secondly, 200 wpc or so, or in that area. I'd bet the ATI 2505, or one of the newer 1805, or 2005, ATI amps would be a good match.

Another thought too is your note on using your existing gear/space for 2 ch. audio. Perhaps TWO amps would be a better approach. One for center surrounds and rears and one for the main 803s. This would be my choice at some point if not initially. Naturally, for a more cohesive sound field, the optimum fix is same speakers all around, and the same flavor power all about too. ?? Well, it is a goal, but not always done 100%. Truth be told you can do pretty well with some compromises to that theme too.

Try also to minimize other diffs too if a pair of amps is sought out... like interconnects and power cables & speaker wires.

I went your route somewhat but in reverse. Adding a two ch amp first. Then, felt for myself, a multi ch amp would be best and as above, more congruent given my speaks are closely mated all around. My current 5 ch amp however will only drive 3 ch of my system, L, C, & R, WITH the initial SS amp driving my rears in a 5.1 affair.

Why? Two reasons... it has a better sonic thumbprint than the Odyssey Stratos Plus +, and it allows for more coherence in the important area. A third aspect is that with many multi ch amps, and mine in particular, using less of the ch at one time allows for a higher power output across fewer channels.

What about the other two ch of the 5 ch amp? I really am not sure how I'll use them.

Good luck.

If you want to 'wake up' bass in your speakers I suggest to look to power them up in 500w/ch amplification range.
I've got my itchy hands to upgrade to Wyred4sound SX500 monos from BCarver Sunfire SRA(250W/ch) which I also can recommend to you.
BTW if you're interested in Sunfire SRA(which is much better match then your current amp) drop me a note with possible offer(open).

I though Marantz made a multi channel amp in its' reference series, but I was wrong. Here is a great 3 channel amp that would sing with your B&W's:
Krell 3 channel

"Is there any particular logic related to amps whose power doubles into 4 ohms? Are there particular Marantz models recommended?"

It shows good power reserves when your amp can double its 8 ohm power rating when going to 4 ohms.

msetexas
>

IMO & IME... power amps which have great power supplies with an abundance of power storage capacity, are as good or better than those which double down their power with regard to impedance drops.

For ex. Krell vs. BAT amps.... Krell doubles output with a halved impedance load.. My KAV250 went to 500wpc at 4 ohms.

My previous BAT VK500 W/BAT pack opt.... put out the initial 250 as the Krell, but at 4 ohms less than 500wpc.

Theoretically you possibly could drain or use the total 500 or 440 wpc from each amp... but logically, with 89-90Db speakers like BW 803s, continuous power outputs of those levels simply won't occur with logical use.

Even some incidental peaks of high freq under sane listening conditions should fall short of the top rated output of either amp.

So there's that... simple doubling of power output is not indicative of any amp being considered either good or bad. Theres more to it. I sold off my 9NT + kav 250 due to it's sonic signature. Not due to power issues.

The BAT vk500 sounded worlds apart better.... and should have perhaps if $$$ means anything. The Krell then was about $3K new. The BAT was about $5.9 new.

Other than sound, I feel it was the power supply and design topology of the BAT which made that diff for me. KAV 250 = 45lbs.... BAT vk 500 = 105lbs. Where's the beef? it's in the power supplies or isn't. digital amps aside.

If you like Marantz' sound maybe you should look into McIntosh, odyssey, Butler, or ATI. Of those only ATI doubles down power with halved imp, though. All however sound very good.

Blindjim-
I was stating that an amp that doubles its power with a 4 ohm load is a simple way to know if the amp has good reserves. Is this not correct?
I was not using this to state whether the amp sounds good or not.

Srwooten
it's as good as any I suppose. Not too many makers publish their power reserve capacities thoroughly IMO.

I sought merely to broaden the viewpoint by injecting some other facts. interjecting there are more criteria to this than noting if amps double up their outputs if speaker imp halves.

As fair a rule as is that, I've found with conventional transformer coupled output amps, I look at the over all weight... now. it indicates to me a general rule of thumb that serves me pretty good, as it speaks about the build of the amps power supplies most often. great amps have great power supplies more often than not.

Also the weight of an amp is not a physical worry for me, usually. It is for some I'm sure.

Voice, input impedance, topology, power reserves, negative feedback or no, are important things I look at when deciding on amplification. To buy an amp however it may not meet my expectations in those regards.

My latest amp acquisition for ex, meets but a few of my short list desires for what an amp needs. it's not heavy, doesn't have enormous power resivoirs and isn't my typical choice of transformer coupled output. In fact it is dainty IMO by my usual amp standards, but the sound and performance exceeded my expectations. A lot. it's price exceeded my predetermined budget too! IMO that's usually what happens to me though.

it's not eye candy either until energized and the lights are off. otherwise it's pretty plain and sort of dull looking as amps go. It's my first 'hybrid' amp too.

I was avidly seeking out an ATI amp for the last few months and a couple others. I almost pulled the trigger twice but both deals weren't quite to my own personal needs. Or this new TDB 5150 wouldn't have gotten here at all.

Hope that helps clear things up.

Thanks BJ-I hope you like your TDB, it looked great online. Please update your page and let us know.
Steve

Thanks much.

update?

I jotted down some initial items and posted it yesterday... then saw this and responded. Once I get a bit of time on it in various ways I'll publish more, but it does sound really good.