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.

one amp will do the trick when the panel and sub posts are jumpered (they come with brass jumpers installed), but using seperate amps for each will relieve the treble amp of the strain of driving the bass woofers, which, in the vista are passive, i THINK - double check that.

a quick check of the specs on the yba 2 makes me think it would be more than enough to handle driving both the panels and the woofers at normal levels, but 1) i don't know if it's stable into lower impedences and 2) i have no idea how it would sound with the vistas or any other speaker.... it's power ratings are plenty, though.

one more caveat: i'm assuming that the specs i saw are for your amp, but i have no way of being sure about that.

i think it said 140w into 4 ohms, which is totally fine.