Class A 30 Watt Amps: Are they enough to drive my book shelfs?

I use a Pass Labs X150.5 on Vandersteen Model 5s.  The meter has never moved out of class A.  Its sounds plenty loud for me.  Dance club loud, no.  But plenty loud for home use.

I ran my Pass xa30.5 with a pair of KEF reference 107s with zero headroom issues. They were 90 dB efficiency and presented a 4ohm impedance.

I honestly think your bookshelves will be fine with the 30.5
Its a marvelous amp and hopefully the last one i ever buy.

In real life a 3 dB gain is not much (and you need to double the power to get it). 3 dBs is generally regarded as the minimum change most people need to hear a difference when playing music. Play around with an AVR with the volume calibrated in dBs. Go up and down 1 db on the dial. I doubt you will hear a difference. And when you are listening and someone asks you to "turn it up just a little" if you turn it up 1 dB they will look at you funny.

People are way too hung up on watts. In most cases it is just a marketing ploy. Why would you buy a 100 amp receiver when you can get a 160 amp receiver? But what they don’t tell you is you will never hear that difference. Doing the calculation those 60 extra watts will only give you an extra 2 dBs when playing both amps at max volume (just before clipping). If you can hear that difference you have better ears than I do.


An amp having an ample power supply and good reserves to power the peaks are way more important than published watts.   From what I hear the OPs amp has a great power supply and reserves. I would prefer it to a 100 watt amp with an undersized power supply and cheap power caps.   He should be fine.

I could be wrong, but I thought the Pass Labs XA 30.5 was a true Class-A amplifier, and true Class-A amplifiers don't have headroom.

elliottbnewcombjr179 posts11-08-2019 12:05pmtubes, transistors, transformers, capacitors, ... are all relative to the rated amount of power within certain specs. All are sized to achieve a price point. Other components are designed to deal with ... heat. If an amp truly could produce more power within specs, certainly the manufacturer would publish that capacity. It ain't so. Measured distortion prevents a larger rating.