I have finally connected my amp with a pair of speakers both with same ratings. Since I'm no longer interested to buy an active subwoofer, I browsed for car subwoofers and found some which would suit me. Since the amp supports bridging I've decided to connect the subwoofer (400watts peak) (4 Ohms) but I was told that to do this I has to switch to MONO and lo longer stay in STEREO mode I got confused because mono is itself a 1channel output whilst stereo is itself a 2channel output and IMHO I think I would achieve more quality using STEREO.

Can you please suggest me the best thing to do !

Only the subwoofer would be in mono.

Low freqs are directed to the subwoofer, other frequencies are still directly in stereo the the left an right reproduction apparatus.

The amp states that it would be bridgeable only in MONO therfore I think that all the speakers will turn in mono !

Why do you think the subwoofer will only be in mono ?
Will there be any quality losses ?

In my mind there's no clear picture of your equipment and wish, but:
The human hearing is not able to determine the spacial source of very low frequencies. Thus having the bass in mono does not reduce the overall quality, if combined with appropriate stereo speakers for the mid and high frequencies.
What I clearly know is 5.1 system and this is similar to a subwoofer system:
Usually, the amp has to have 6 chinch outputs, leading to the subwoofer: Front right, front left, rear right, rear left, center and subwoofer. From the (active) subwoofer the cables lead to the other single speakers.

But with this you haven't answered any of my doubtful questions.

1. I gather from your posts that you have only 1 stereo amp and you wish to extend the lf by adding a sub to your existing setup WITHOUT additional amplification?
It is impractical to add a sub (<100hz) using passive Xover; the inductance/choke/coil value would be large (=$$$)

2. Bridging your EXISTING amp won't help

Before : stereo amp = L channel > left speaker
= R channel > right speaker

After : stereo amp > bridge mode > L speaker OR R speaker (NOT BOTH)

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You would need 2 stereo amps to get stereo if you bridge.IMHO you are confusing the 2 issues ie bridging & adding sub.Using a car sub is not a good idea as they are designed for relatively small car volumes.

I am gathering from your posts that you are after more 'punch' in the bass and not lf extension in the pure meaning of 'sub-woofer'? I think you need to state CLEARLY what you expect to achieve(hear)....a list of what gear you have would help

rgds

Quality is main target, and since I like bass I was wondering of a powerful subwoofer to hook up. Thats all !

Sorry, maybe I'm wrong here. I think I said something referring to this:

Yeah don't worry i won't bridge or add any subwoofers at the moment.
I was only a little confused about the bridging thing, still unsure.