Geoff, not sure if it's clear that the LOWER the input sensitivity number is, the more sensitive the amp is, and the higher the volume level that will result from a given input, at a given volume control setting. 600 mv presumably represents the input signal level that is required to drive the amp to its maximum power rating, **with the volume control turned up all the way.**
As you indicated, some integrated amps have rated sensitivities in the area of 1 volt or more. I would expect those to often have problems when used with phono sources, though, depending on the power rating of the amp and the sensitivity of the speakers. Many other integrateds are much more sensitive, down to 200 mv or even less. Keep in mind that separate power amps often have sensitivities in the area of 1 to 1.5 volts, and the line-stage preamps they would be used with often provide gains in the area of 10 to 20 db, corresponding to a voltage multiplication of 3 to 10 times.
Your cartridge has a rated nominal output of 4 mv. The phono stage provides a gain factor of 100 (corresponding to 40 db). So under the standard cartridge test conditions, which represent a high volume level in the recording, the integrated amp will see an input of 400 mv, less than what is required to drive the amp to full power with the volume control turned all the way up. Really loud volume peaks in some recordings will cause the cartridge to put out significantly more than 4 mv, so at those times you will be able to drive the amp to full power. But I don't think it is surprising that you generally have to set the volume control at or near the top of its range.
Regards,
-- Al
As you indicated, some integrated amps have rated sensitivities in the area of 1 volt or more. I would expect those to often have problems when used with phono sources, though, depending on the power rating of the amp and the sensitivity of the speakers. Many other integrateds are much more sensitive, down to 200 mv or even less. Keep in mind that separate power amps often have sensitivities in the area of 1 to 1.5 volts, and the line-stage preamps they would be used with often provide gains in the area of 10 to 20 db, corresponding to a voltage multiplication of 3 to 10 times.
Your cartridge has a rated nominal output of 4 mv. The phono stage provides a gain factor of 100 (corresponding to 40 db). So under the standard cartridge test conditions, which represent a high volume level in the recording, the integrated amp will see an input of 400 mv, less than what is required to drive the amp to full power with the volume control turned all the way up. Really loud volume peaks in some recordings will cause the cartridge to put out significantly more than 4 mv, so at those times you will be able to drive the amp to full power. But I don't think it is surprising that you generally have to set the volume control at or near the top of its range.
Regards,
-- Al