How important is S/N Ratio....?

135db and I can hear it!!!!!
Human hearing dynamic range is somewhat lower than that...
A sound at 135db would burst your ear drums or render you incapable of appreciating hi-fi.
Therefore, a sound '135db' down is either....So far below hearing limits as to be nearly, if not completely unmeasureable OR referenced to a sound so loud that it would Hospitalize you.
I am not even going to go to the 'Weakest Link' end of town where who cares if your caps are 135db, when your output devices and the REST of the circuitry are no better than 100db?
I repeat:: Specs are nearly meaningless. If you purchase something based on specs rather than quality, you may be surprised. It could go either way!

Magfan - large dynamic range of 120dB or more is absolutely necessary to reproduce real sound of the large jet planes taking off when I see it on TV.

As for "More Power" I would suggest "Less Power".

Au contraire baby, More Power is More Mojo

-135 db down is meaningless only when....there is no sonic difference discernable....but when I add two low noise PSU capacitors and 10 ultra low noise caps to a SS amplifier and the sound is unmeasurably better...I guess the poor guys that spend 30K for a amplifier can't tell the difference either...BTW the upgrade cost me 750 bucks....including labor.

Wavetrader,
I will love to upgrade the components n my components too, but have you ever wondered whether it might be detrimental to the flow of current when you use different solders to what was originally used on the circuit boards? Like the interactions between different alloys and the also the matter of whether the components will be mounted as stably as the ones originally supplied. Nowadays it's all surface mount. These are the main concerns that are preventing me to do such risky modifications. But if the amplifier is made by hand when purchased, I won't have any problems with that.