Yes, the machine type and method of connection determine the cable type needed. Yes, cable quality can be heard ! Good cables are a wise investment for your listening experience, highly recomended !
A) Optical cables
Also known as Toslink cables, these special cables contain fiber optic "wire" that transmits data as light. The dat machines are fitted with toslink connectors which translate the light pulses to electrical ones.
B) Coax cables
75 OHM cable with RCA connectors on each end. Through a standard 300 OHM RCA cable will usually work, it is important to use the proper impedance cable to minimize jitter when transferring data.
C) AES/EBU
This digital interface is used on most professional machines. It looks like a standard XLR connector. The cable is 110 OHM impedance so once again a higher impedance audio XLR cable shoud not be used. The advantage of using the AES/EBU interface on the many Pro machines is the ability to "strip" SCMS bits from the data stream during a transfer and make an SCMS free copy of any tape.
D) Sony TCD-D3/7/8
In Order to connect the popular Sony DAT walkmans to another machine for data transfers one must obtain a special cable. This cable translates the Sony 7 Pin I/O to a standard S/PDIF Coax or Toslink optical signal. Several Hi-Quality cables are available to do this , the Sony optical cable, model number POC-DA12 or the coax connector, model number Rk DA10.
Both of these cables are powered by the Sony unit. The optical cables provides both input and output, however , the coax cable is an input only. If one has the luxury of AC power one can use the Sony RM-D3K (list price $300) interface adapter box for both optical and coax digital interfaces.
Oade audio manufactures a special cable which provides you with a coax digital input & coax digital output simultaneously. This allows you to record from a Sony portable onto a another DAT machine digitally. It also provides a coax digital output from the Sony SBM-1 super bit mapping a/d convertor. Perhaps the most popular use for this cable is in the field (at live shows) where there are a number of DAT tapers with high quality microphones. This cable allows you to Daisy chain portables together. SCMS will not be a factor when daisy chaining machines for a live feed. Jitter will, however, limit the number of machines you can tie together. I have had as many as 12 Sony DAT machines all receiving pure digital signals running off the same pair of microphones! This cable facilitates getting a patch at a show because your deck can receive a digital signal & pass a digital signal on to the next person.