Better to get a good efx pedal instead and use the amp's clean channel. The difference between tube and trans for clean sound is not that discernable.
Except if you play clean only of light distortion, the tone will shine on a good tube amp.
For metal sound, I think there is not much difference on a practise grade amp, a trans amp is actually more suited for a metal sound. Due to it's reliability and price, the trans wins on this field.
these days, you get pedals with amp modelling, all you need is a clean channel to work out the tone you want on the efx.