Howard - help! Just to be clear by overload (on my Meridian 101B preamp) I mean you don't have to push the volume control very far on either CD or LP to get a decent volume. I do not want to use an attenuator if I do not need to. I thought you meant by overload that you get loads of volume at twenty to ten?
Overload is a characteristic typified by distortion and harshness. This is usually quite audible in extreme circumstances but sometimes too subtle to hear directly at lower levels. You somehow know it's there but can't quite pin it down.
This is separate from volume controls that don't need to be advanced very far in rotation in order to get an acceptable volume of sound. There is unfortunately but unsurprisingly no uniformity of rotation of a volume control between makes other than of course no volume control is rotated twice around the clock in order to achieve the full volume. Or put differently, some volume controls might move from say 9 on a clock face around to 6 on a clock face between minimum and maximum i.e. 75% rotation. Others might be say 90% or even 60% rotation between maximum and minimum volume. It varies. Okay, moving on ...
The very strong probability is that the miniscule output from your cartridge is incapable of overloading the MC input unless you were by chance using a very high output MC cartridge into a very high gain (high sensitivity) input module. For example from that era, a Supex 901 into a Meridian Dynavector high-gain module. In contrast, with older equipment built in the era before CDs were available, overload is a distinct possibility - hence the need for inline attenuators..
It is an unhelpful fact of life that because there is no standardization of input sensitivities nor indeed output of MC cartridges, that different inputs (say MC to Tuner to Tape, and so on) will produce different volumes when selected - even if the volume control has not been touched. This is why some more advanced units, especially Japanese ones have facilities to adjust the input sensitivities so that all sources produce the identical sound level to each other at any position on the volume control. Some purist argue that while this might be useful, the additional circuitry necessary to permit this is just one more unnecessary layer between the music and the listener. I hope this helps.
Howard Popeck