they'll never be the same without the lovley tone of a 5cyl

I'm afraid you've all missed the only real option for best noise; the Alfa (Arese) V6!
;-) ;-) ;-)
More seriously, the Volvo 5 pot sounds Ok, though it needs a turbo to really prick up the ears. For the NA versions, a big part of it's disadvantage is you've got to wring it out before it becomes tuneful &, at least on my 2.5 20v'er, that's hard work compared to my Alfa 164 (IIRC :-( ), which throbbed just enough to draw you on before it sang from 3-7k.

Disagree on that. The sound of a 5cylinder at full throttle is fantastic.

For me though, that's the problem; the (NA) Volvo 5 pot doesn't sound enthusiastic until you get over 3k, but the Alfa V6 sounded muscular from idle to redline.
I was going round the Bristol ring road in the Alfa some years ago, in the outside lane I got held up by a boy racer in a saxo or corsa. Kept a proper distance, but after a moment or 2, dropped it into 3rd (still sitting back), at which boy racer pulled straight in ;-)
Wouldn't expect to get the same result in the Volvo; to be fair though, the Volvo's better turning circle is a real benefit in town.

I always liked the sound of the 850 we had when it was started. It had a nice thrum.

Can't blame you for liking those alfas. The engines do indeed sound fantastic.