No one is going to islotate the lat's complety when the hands/arms are involved in the exercise. If the hand/arm link is taken out of any direct lat/back exercise, than it becomes so much more effective. When the point of resistence is on the point of the elbows, rather than pulling with the hands/arms , than if may almost become a pure lat/back movement. And in return, greater muscle growth. Your not going to do that with a T bar, BB, DB or that poorly designed metal mess shown in the photo. The original Nautilus pullover machine is still one of the more effecrtive units made. Some other manufactors have produced similar devices, keeping the resistence where it belongs, on the elbows. There are also straps/web's that are positioned on the point of the elbows when doing cable (sitting) pulls. Can also use a version to use when chinning or pulldowns. Suprising that you can use so much more extra weight when using that shorter, more powerful leverage of the elbows, rather than using the weaker link of the hands/arms. How many times has the grip/arms given out before the lats are really hit to their full potentional (inducing growth/strength) when doing any form of regular rows/chins, etc?
Rather than SS'ing Rows with chins/pulldowns might try doing a set of pullovers (straight or bent) and than rows or chins. Pullovers, in what ever form (BB/DB), pre-exhaust the lats very well before doing row's, chins, etc. Can even do a tri set with pullovers, pulldowns and rows.
If anyone decides to to a 30 rep set for chins, than 10 or 12 reps should be the first goal. Take a rest-pause of 15 seconds and than try for more reps. Continue with these rest-pause breaks until the full 30 are achieved (may take awhile). Breath deep & fully during this brief rest period. Do not hang from the bar, release the grip and relax the hands/ arms, etc for that 15 seconds. !00's can work very well with this style of training for men with serious intent. Good Luck.