Poor bass in Yamaha receiver

[gto127]

I've been working on a High end Yamaha receiver lately & can't seem to figure why the bass is thin. I've eliminated setup issues. In pure direct 2 channel mode same problem. So far I've replaced output bypass caps and resoldered poor joints in powerr supply. I think whatever the problem is may be common to the brand. I was searching AV forums and many Z11 owners had poor or thin bass while others had superb bass. Most Yam receivers I've heard do have very good bass so It's got to be some type failure in some units. If anyone has ran across this in other Yam units with solution it would be appreciated. I've notice the amp sections on these units are almost identical across most models.

[nigelwright7557]

If the amp has any age then I would suspect any electrolytics.
They dont cost much so worth replacing them all.