its not the same, but that doesn't stop you taking the signal directly from the dac to the dock.
The difference with the 6th gen is that the line out is already pretty clean, and stock, the line out is better than the 5,5g, thus the difference in improvement gained between modding the 6th gen would not be as large as they are when modding the 5.5gen.
NOTE, that does not mean the 6th gen is as good as 5.5 gen diymod or imod, or indeed that when modded the 6th gen would be as good or better than a 5.5gen diymod/imod ... you still have the better dac in the 5.5 gen.
it does mean that probably in some peoples experiences, the stock 6th gen is as good or better than the stock 5th/5.5 gen as it is a cleaner signal stock, but dont forget the poorer dac (by all accounts)