Dont piss around just get the Texas Star 500 non variable and run that S9 into it that 40 watts isnt going to hurt it aslong as you keep the amplifier cool meaning AD A FAN there cheap and make the difference between life and death of an amplier Ive run my
HF rigs into my Texas Star 500's with power between 40 and 50 watts
SSB but
AM back it way down 2-4 watts dead key ide stay around 2--3 watts and 20-25 watts forward swing.