Mastering EQ for Phone Speakers

Does anyone have any good insight on making a master sound “good” on iphone speakers? My track sounds great on every speaker system I have tested but I am having a hard time finding the right EQ settings so the Iphone speakers aren’t losing too much information. The track is very classic rock driven with a ton of bass and guitar distortion, it was also recorded to tape which may be playing a factor that I haven’t dealt with yet. Any information would be greatly appreciated!

Thanks.

do a small dip somewhere between 20-40hz. 0.5db go a long way.