Is my YBA amp enough to run Martin Logan Vistas?

That is not actually true, it depends on the speaker. Quads, for example,can be overdriven by too much power. Many electrostatics present a difficult load ; often in the high end. The ML hybrids my friend use to have went down under two ohms in the top end [1.8 to be exact]. If the ML you are talking about has a similar impedance curve then you need to see if your amp is happy with this kind of a load.

yeah, like stanwal says, be sure that your amp is stable into lower impedences. i think my summits go down to around 1 ohm as well.

that being said, i don't think the panels need a ton of power, and if i recall correctly, the woofer in the vista is passive, so you could drive them with a second ss amp if you wanted to, leaving the yba (which i'm not familiar with at all, sorry) to just feed the panel.

you could do a search over at the martin logan forum to see what success other people have had.

cheers.

Do I need to have an amp for the panel and the sub?

I thought the Vista was powered? That would definatley throw a wrench in.

I will check the Logan forum too.