IT was a night of bliss, for lovers of quality American acoustic country music. After an engrossing and entertainingly varied set from the home-based Slightly Bewildered String Band, brother and sister Tim and Mollie O'Brien took to the stage at Whelan's in Dublin last night and produced a performance which frequently sizzled if it did not actually catch fire.

Supported by long-time collaborators Scott Nygaard (guitar) and Mark Schatz (double bass), otherwise jointly known as The O'Boys, the O'Briens were playing the final gig of their short British and Irish tour. Occasionally, they looked a little weary, but they roused themselves for a mighty impressive run-in, providing plenty of humorous banter to smooth the journey.

When they last played here, about 18 months ago, the audience was apparently small. It was bigger this time around and, judging by the reaction, the place will be packed next time. And deservedly so.

Their music has broadened in recent years to a more mainstream sound, as captured on Mollie's fine solo album earlier this year, Tell It True. Yet the bluegrass sound of their childhood years in West Virginia, and the music which brought them to prominence, is still the dominant influence. Indeed, it was interesting that some of the loudest applause was rightly reserved for the more traditional songs.

Much of the material - Alaska, If I Live and Lark in the Morning - was taken from Tell It True, while Tim's Bob Dylan tribute, Red On Blonde, also supplied a number of fascinating readings of well-known Zimmerman tunes.

The harmonies were especially tasteful, as was the playing, with honourable mention going to Tim's dazzling dexterity on mandolin and bouzouki and Nygaard's rippling guitar fills. However, for many it was Mollie's strong clear voice which was the real treat.

When they return, as they promised, they will be sure to make their acquaintance. Too little of the American music we hear comes as pure as this.