Here are a few integrates that have simulated easy load tests done by Stereophile most don’t become tone controls that you and others have mentioned.
Belcanto Ref600 good
https://www.stereophile.com/images/916BC600fig1.jpg
Lux L509X good
https://www.stereophile.com/images/518L509fig01.jpg
BelCanto Black good (fine plot)
https://www.stereophile.com/images/615BCBfig12.jpg
This T&A V10, didn’t fair too good
https://www.stereophile.com/images/archivesart/V10FIG01.jpg
Ayre AX-5 good (much finer plots)
https://www.stereophile.com/images/713AX5fig01.jpg
Peachtree Nova 300 was good but droops up high.
https://www.stereophile.com/images/517PN300fig01.jpg
Benchmark AHB2 also good (fine graduation plots)
https://www.stereophile.com/images/1115BAHB2fig01.jpg
Cheers George
Belcanto Ref600 good
https://www.stereophile.com/images/916BC600fig1.jpg
Lux L509X good
https://www.stereophile.com/images/518L509fig01.jpg
BelCanto Black good (fine plot)
https://www.stereophile.com/images/615BCBfig12.jpg
This T&A V10, didn’t fair too good
https://www.stereophile.com/images/archivesart/V10FIG01.jpg
Ayre AX-5 good (much finer plots)
https://www.stereophile.com/images/713AX5fig01.jpg
Peachtree Nova 300 was good but droops up high.
https://www.stereophile.com/images/517PN300fig01.jpg
Benchmark AHB2 also good (fine graduation plots)
https://www.stereophile.com/images/1115BAHB2fig01.jpg
Cheers George