Audio Systems: headphones/microphone, behringer xenyx 802, headphone amp

Question
Hi,
Can you tell me if there is anyway to listen to a set of Roland V9 drums and a bass (or acoustic) guitar with a set of headphones that will also allow both users to hear one another when they speak but to also hear both instruments being played? I've seen headphones with built in mics and I've tossed around the idea of two seperate mics but then how could they hear one another talk? I've had one person tell me I'd need a headphone amp as well as a mixer in order to use more than one set of headphones but others tell me I just need a mixer....??...Ultimately I was hoping I could buy a Behringer Xenyx 802 and that it would be capable of plugging into the amplifier, having two sets of headphones plug into it, the cd player that is currently plugged into the amp (or possibly a cd recorder in the future) and then I would only be left with the problem of not being able to hear between one another when speaking, unless I can plug two mics into the mixer and have them both run through the headphones with the sound of the bass and drums??  I know this seems extreme but for now these are being played in a basement of an exective condo and I want to purchase this as a Christmas gift for my boyfriend and his son because I'm afraid that all of the soundproofing he's been working so hard on for the last 2 weeks is not going to make enough of a difference that the neighbours won't complain. They complain when the tv is too loud now so I thought if there was a way that they could play together it would make a great gift for them. Any help and/or suggestions at all would be greatly appreciated.

Thanks so much :)

I know this is going to seem extremely complicated but

Answer
It seems like your making your life difficult. The should be using earbuds in one ear and monitor the other instrument with the other. Believe it or not many professional musicians, when they are faced with these very same circumstances, resort to this method.

The headphone/mic idea is strictly for amateurs. The correct way of doing it is to use a mixer with one or two foldback buses (one for the bass and the other for the guitar) or the mains for the guitar and an aux for the bass. The mixer would feed a headphone amplifier with multiple outputs. The musicians can then separately control the balance and volume.