I find myself about to write what Piezo described so I ditto his excellent description... I also find triode (I use VTL 450s) to be lush, exuding a luxuriant 'thereness' and beautiful instrument separation - particularly notable in massed strings, and choral works where individual voices both make up the group and somehow seek to escape it. On SACD, triode can be downright scary. I appreciate tetrode however for 'live' rock music played at 'concert' SPLs, where it seems to better convey the sense of being too close to the stage for one's own good. I used both modes evenly at first but use it in triode most of the time now - more shivers and stupid grins (though tetrode on music with BIG dynamics can leave me breathless).
Piezo, have you used a different preamp with your system? Do you find the 5.5 affects your choice of use of triode or tetrode? Would you recommend it (or another preamp)? I use a passive attenuator and wonder if that is one reason why I lean to triode so much...
