I can highly recommend the PS Audio Powerbase - for me it was a definite and clear improvement ito of sq.
Worth the money if you can pick one up used for around $500-$600.
PS Audio's spiel:
The PerfectWave PowerBase combines a dual diffused isolation base with a one-way-gate power conditioner into an elegant, component level product base. Use the PowerBase for source, control or power equipment and enjoy a remarkable improvement in the space between instruments,...