Yes Twb2, unless your prepared do your homework to get the right amp with ELS's, they will be a comprimise at the low impedance + difficult phase angles frequencies, as Roger Sanders ( in his White Paper http://sanderssoundsystems.com/technical-white-papers/172-tubes-vs-transistors ) and I have outlined a few times above, that many tend to be blind to.
Here are two more and there are many more on all brands of ESL's
Martin Colloms from HIFI Critic Report on the Quad ELS-2805:
"Amplifiers with more
than 0.6 ohms output impedance (which most tube amps can be) will cause shifts in tonal
balance, namely recessed over-sweet treble, and some
degree of lower midrange boom and bloom."
And also Keith Howard from HIFI News report on the Quad ESL-2912
" Impedance phase angle at low frequencies
is high enough to lower the EPDR (equivalent peak dissipation resistance)to a minimum ohm of 1.4ohm at 69Hz, but as the ESL- 2912's impedance will be level-dependent at LF the dips to 3ohm modulus at 7.5kHz and to 1.6ohm EPDR at 11.lkHz are more relevant and suggest a moderately difficult amplifier load."
Cheers George
