Alistair Robertson-Aikman designed the SME precisely with the Ortofon SPU in mind (which is why he adopted the Ortofon arm/cartridge coupling connector at the arm end - originally SMEs were sold without a headshell, the latter being an optional extra). Thus they should be capable of balancing out the weight of SPUs (even those SPUs without the transformer are fitted with an additional weight internally so as to weigh the same as the SPUGT).