I have tried to purchase one AKG K1000. I was informed that there are bass heavy version and bass light version. I was informed that the bass heavy
version is those with the SN below 4000-5000. During my search of the bass heavy AKG K1000, I met one of the seller of AKG K1000 in Germany who is working
with the SAC.de which builds the amplifier for AKG K1000. He knows a lot about the AKG K1000 because he has been working with the AKG K1000
everyday. He said that there was no bass heavy or bass light version and we cannot go by serial number. He also mentioned that there
are probably US version which have more bass and European version which have less. In his experience he said that there was no problem
with the bass with AKG K1000 at all when using appropriate amplifier. However he also mentioned that there may be some problem with the driver
of the older one . He said that the AKG K1000's with the serial number more than 10000, the sound quality are not as good as the SN less than 10,000.
I think we need to ask the opinion of those in Europe to clarify the myth of bass heavy or bass light version of the AKG K1000.