Used AI3A. If your new to this product there a a few things you should know. The 3A can be a wonderful sounding preamp even with OEM tubes. The thick main PWB and the aluminum casework are very nice. The sound is typically wide and detailed. Scratchy attenuators, selectors, and noisy outboard power supplies are signs of needed repair.
It's important to know the serial number of the unit your thinking of purchasing. A call to AI with the serial number will help you discern the age and level of upgrade. I believe the Gold phono board is the same throughout, the main board was upgraded around 1999-2000. The attenuators and selectors were also upgraded. Again, a call to AI will be very helpful regarding the need and the costs for upgrades.
It's important to know the serial number of the unit your thinking of purchasing. A call to AI with the serial number will help you discern the age and level of upgrade. I believe the Gold phono board is the same throughout, the main board was upgraded around 1999-2000. The attenuators and selectors were also upgraded. Again, a call to AI will be very helpful regarding the need and the costs for upgrades.