I doubt the Laguna are the weak part of the system. A friend's Altec A7's are IMO still one of the best speakers I heard to date and that includes many modern hornspeakers, such as the Avantgarde and others.
You may want to look into modifying and rewiring the crossovers of the Altecs. Otherwise the amp may not be an ideal match, try some different SET amps if you can.
Finally the SME arm is a little lightweight for the low compliance Shelter cartridge and not an ideal match which will show in the bass most. The Shelter is a nice cartridge and the SME arm is nice too, but the match is far from ideal with respect to arm- cartridge resonance. I would consider a different cartridge for the SME arm.
You may want to look into modifying and rewiring the crossovers of the Altecs. Otherwise the amp may not be an ideal match, try some different SET amps if you can.
Finally the SME arm is a little lightweight for the low compliance Shelter cartridge and not an ideal match which will show in the bass most. The Shelter is a nice cartridge and the SME arm is nice too, but the match is far from ideal with respect to arm- cartridge resonance. I would consider a different cartridge for the SME arm.