I currently have a spiro mittel E(low C)/A and Permanent D/G on my bass. The perms work great for solo stuff, but I'm hearing a darker sound latley, so I'm going to shoot for that. Also, the Spirocore extension string feels a whisker too heavy for me as I've been playing a lot latley. I was thinking of doing a Spiro Weich Extension string, Spiro weich A, and flexocore light gauge D/G. Is a flexocore pizz entirely too short and thumpy for jazz playing or is it the kind of string that can worked around using good amps and technique?