Both are two classic preamps but never played with them. I'm looking for warm and clear sound. Which one is better for my Ric and my EBS amp?
EBS amps are known for warm and clear sound. What specifically are you hoping an external preamp will do for you?
My experience with those preamps (admittedly all from >20 years ago) suggests that if you're looking for any tonal coloration from the preamp, the SWR would be the preferred choice...not because the Grand Prix necessarily achieves the "warm and clear sound" you're seeking, but because the PB1 is about as neutral as a bass preamp can get.
it it's just warm and clear you want, the PB-1 certainly would fit the bill. it has lot's of (usable) features and is built better than any preamp I've ever owned or seen. the Grand Prix has an overdrive circuit, never owned one so I can't comment on how they sound or perform
No experience with the Grand Prix. Prior to buying my SVT-CL I used an SVP-1500 driven by a PB-1. I picked up the PB-1 for under a bill. It is a great preamp. I love the Parametric EQ on it. The built in X-over can be handy if you are running with a two channel amp and multiple cabs. Tonally I don't know the differences between the two units but if you are looking for a lot of bang for your buck. PB-1 all the way.