Roger McGuinn, Gene Clark and Chris Hillman have been reduced to opening for third-rate imitations of their old group, The Byrds. Last night, the trio opened for America at the Merriweather Post Pavilion.

Last night McGuinn, Clark and Hillman sounded a lot better than they did on their spring tour and record. McGuinn played more of his droning electric 12-string guitar, and Hillman was once again soloing inside the beat at both ends of his bass. The real instrumental star, though, was lead guitarist John Samabtaro, whose solo of quick, spinning notes climaxed the band's new single "Surrender to Me."

But the band still fell short of the old Byrds. The biggest gap was in song-writing. McGuinn's recent tune, "Don't you Write Her Off," was catchy but clearly lacked the substance of "Chestnut Mare," his old Byrds' song which soon followed. The unidsputed highlight of the whole evening was the encore medley of three Byrds' hits: "Mr Tambourine Man," "Eight Miles High" and "I'll Feel a Whole Lot Better." McGuinn played his only lead guitar of the night, Hillman was all over his bass; four voices soared with that fine balance between folk and rock.

America, now just a duo with Gerry Beckley and Dewey Bunnell, also combined folk and rock elements, but only the blandest aspects of each. Last night they were backed by five musicians, and recreated the polished production of the old hits like "Ventura Highway," and their new single, "Only Game in Town." Bunnell's voice had no range; Beckley's had no depth, and neither has written strong melodies. They support the theory that mellow is a euphemism for mediocre.